Transport behavior of water and ions through positively charged nanopores

Abstract

• Investigating the application of charge-modified nanopores in water-ion separation. • Studying the effect of positively charged nanopore on water permeability. • Unveiling the complex interactions between charge-modified nanopore and hydration ions. Two-dimensional nanoporous membranes are promising materials for seawater desalination. However, the effect of nanopore charge properties on desalination performance, especially on water permeability, has not yet been systematically investigated. In this work, molecular dynamics simulations were carried out to elucidate the impact of nanopore charge modification (variated from 0 to 1.0e) on water permeability and ions conduction. The highest water permeability was observed when the modification was approximately 0.25e. The nanopore charge conditions significantly impacted water dynamic behaviors, leading to the transition of water transport processes from continuum state to non-continuum state with the increase of nanopore charge. In addition, we found that the positively charged nanopores not only effectively impede cation permeation, but also strongly impact the diffusion behavior of anions. This work unveils in-depth insights into the mechanism of saline water transport through the charge-modified nanopores and highlights the importance of the nanopore charge states for desalination. Meanwhile, it provides useful guidelines for the rational design of optimal nanoporous membranes in the future.