Ultra-high permeable phenine nanotube membranes for water desalination

TL;DR

This study demonstrates that phenine nanotube membranes exhibit exceptionally high water permeability and complete salt rejection, making them promising for advanced water desalination and nanofluidic applications.

Contribution

The paper introduces the use of phenine nanotube membranes for water desalination, showing their superior permeability and salt rejection through molecular dynamics simulations.

Findings

PNT membranes completely reject salts.

Water permeability is an order of magnitude higher than existing membranes.

The microscopic mechanisms of transport are elucidated.

Abstract

Nanopore desalination technology hinges on high water-permeable membranes which, at the same time, block ions efficiently. In this study, we consider a recently synthesized [Science 363, 151-155 (2019)] phenine nanotube (PNT) for water desalination applications. Using both equilibrium and non-equilibrium molecular dynamics simulations, we show that the PNT membrane completely rejects salts, but permeates water at a rate which is an order-of-magnitude higher than that of all the membranes used for water filtration. We provide the microscopic mechanisms of salt rejection and fast water-transport by calculating the free-energy landscapes and electrostatic potential profiles. A collective diffusion model accurately predicts the water permeability obtained from the simulations over a wide range of pressure gradients. We propose a method to calculate the osmotic water permeability from the equilibrium simulation data and find that it is very high for the PNT membrane. These remarkable properties of PNT can be applied in various nanofluidic applications, such as ion-selective channels, ionic transistors, sensing, molecular sieving, and blue energy harvesting.