Theoretical investigation of electrodialysis-driven salt ion transport in pillared graphene membranes

Electrodialysis (ED) is a sustainable desalination method that leverages electric fields to drive ion separation, offering advantages such as energy efficiency and reduced environmental impact. While nanomaterials have shown promise for enhancing ED membrane performance, the ion transport mechanisms in three-dimensional architectures remain insufficiently understood. In this study, we employ non-equilibrium molecular dynamics (MD) simulations to investigate the performance of pillared graphene (PG) membranes, composed of graphene sheets and vertically aligned carbon nanotubes (CNTs), under varying electric field strengths. The simulations revealed that an increase in electric field intensity significantly enhances the efficiency of Na and Cl ion separation within the PG membrane structure. Specifically, stronger electric fields reduce the energy barrier for Na and Cl ion movement through the CNT channels, leading to higher self-diffusion coefficients and more effective ion permeation. Moreover, our findings indicate that Cl ions exhibit higher mobility than Na ions under identical conditions, suggesting an asymmetric response to the applied electric field that could influence selective ion transport in ED applications. The findings provide molecular-level insights into how PG membranes facilitate selective ion transport, a critical factor in optimizing ED performance for desalination and water purification applications.