Hybrid graphene oxide-graphene membrane for efficient water desalination: Insights from molecular dynamics simulation

Abstract

In the field of reverse osmosis (RO) desalination, layer-by-layer assembled graphene oxide (GO) membranes have emerged as a promising innovation. However, the swelling of these membranes remains a critical barrier that affects their performance and long-term stability. To address this challenge, our study investigates the potential of hybrid GO and graphene (G) membranes to reduce swelling and increase overall performance through molecular dynamics simulations. Our findings reveal that the G/GO/G/GO hybrid membrane outperforms others, demonstrating a water permeation rate of 69.2 L/cm2/day/Mpa, exceeding alternatives, and boasting 100 % ion rejection efficiency, with a channel inter-layer distance of 8.77 Å. Moreover, the combination of hydrophobic G sheets and hydrophilic GO sheets reduces swelling compared to pure GO membranes. Furthermore, the analysis of water velocity within the hybrid GO/G membrane reveals that the velocity profile is no longer symmetrical, unlike in the pure G and GO membranes, and the maximum velocity occurs in close proximity to the hydrophobic sheet. Additionally, increasing the mass of G sheets in the hybrid GO/G membrane, enhances water flow, while a higher GO sheet ratio reduces permeation. Our study reveals the distinct characteristics of pure GO and hybrid GO/G membranes and their significant impact on water desalination technology.