Molecular Dynamics Simulation of Nanostructured Grazynes for Water Desalination

The search for selective desalination membranes is a topic of great importance for producing freshwater. Here, the potential use of grazynes  2D C-based porous membranes that combine graphene stripes linked by acetylenic linkages  as desalination membranes has been explored using molecular dynamics simulations. Five different grazynes with pore sizes between 1 and 21 Ų were considered under pressures of 150 to 210 MPa. Two of these grazynes proved to be completely impermeable, while the other three  [1],[2]{2}, [1],[2]{3}, and [1],[3]{2}  demonstrated a clear water flow that increased almost linearly with pressure. Among these, [1],[3]{2} showed the highest water flow due to its larger effective pore size, which led to the passage of Na⁺ and Cl^- traces. The [1],[2]{2}-grazyne proved to be the best-balanced membrane between water flow and salt rejection, achieving even perfect salt rejection in the high-pressure range. When compared to other C-based membranes, grazynes achieved competitive results, reaching permeabilities of ca. 15 L·cm^-2·day^-1·MPa^-1 under conditions of perfect salt rejection. Even at the highest pressure where salt ion permeation was observed, the resulting permeate salinity remained in a range associated with poor taste by the World Health Organization (WHO) while still being potentially suitable for irrigating many crops according to the Food and Agriculture Organization of the United Nations (FAO) salinity guidelines. These results position grazynes as candidates for desalination membranes and open pathways for further investigation.