Molecular dynamics insights of the removal of lead and cadmium from aqueous solution using functionalized graphene nanosheet

Functionalized graphene (GRA) based membranes have emerged as promising candidates for ion separation owing to their tunable surface chemistry and ultrathin architecture. A nanopore was introduced into the membrane surface and subsequently functionalized with fluorine (-F) to create a selective transport pathway for ions. This functionalization was designed to modulate ion-pore interactions, enabling controlled and selective ion permeation across the membrane during the separation process. In this study, classical molecular dynamics (MD) simulations were employed to investigate the selective permeation behavior of heavy metal ions through the nanoporous GRA under an external electric field. The diffusion coefficients of Pb²⁺ and Cd²⁺ ions were found to be 1.317 × 10^⁻9 m²/s and 1.129 × 10^⁻9 m²/s, respectively. The outcomes revealed that a greater number of Pb²⁺ ions permeated through the functionalized nanoporous membrane compared to Cd²⁺ ions. These findings provide an atomic-level insight into the mechanisms of selective transport of heavy metal ions for advanced water purification.