Computational Assessment of Water Desalination Performance of Multi‐Walled Carbon Nanotubes

Abstract

The desalination performance (water permeability and salt rejection) of both uncharged and charged multi‐walled carbon nanotubes (MWCNTs) is computationally assessed by means of pressure‐driven molecular dynamics simulations. It is shown that the performance of these materials surpass that of the widely used polyamide reverse osmosis membranes and are even better than 2D materials such as nanoporous graphene or boron nitride. The molecular origin of the fast water transport through MWCNT materials is ascribed to a synergic effect between the existence of a single water layer and low friction between water molecules and the carbon nanotube surface. Furthermore, for charged MWCNTs it is highlighted that the electrical charges on the nanotube surface result in a strong anchoring of ions and water molecules. This leads to clogging of the annular region between nanotubes and the generation of a force, which makes water transport through the central channel of the MWCNT faster.

Molecular modeling of thin-film nanocomposite membranes for reverse osmosis water desalination

“…10), which gave rise to clogging of the annular region while enhancing fast water transport within the inner tube. 147 The computationally designed MWCNT membranes showed superior water permeability and salt rejection compared to PA membranes and even graphene and BN nanosheet-based membranes.…”

“…Compared to uncharged ones, SWCNTs with a low charge density on the rim produced a slight increase in water flow and ion rejection, while those with a high charge density yielded a significant improvement in salt rejection (calculated via eqn (6)) (beyond 95%) and a high water permeability of 425 L m −2 h −1 bar −1 . While designing a new class of MWCNTs with positive and negative charges, Ghoufi and Szymczyk 147 investigated the influence of surface modification on water transport and ion rejection (Fig. 10).…”