(501d) Selective Enhancement of Water Evaporation from Salt Solutions Using Graphene Nanopores: A Potential Eco-Friendly Approach for Desalination Applications

The increasing severity of global water scarcity has spurred scientific research towards the search for clean and sustainable water technologies. Among various approaches, evaporation-based solutions have garnered significant interest due to their low energy consumption. Recent experimental and simulation studies have reported a 10-30 fold enhancement in water evaporation flux through Ã…-scale graphene nanopores. However, the potential application of these nanopores in enhancing evaporation from salt solutions remains largely unexplored. In this study, we investigate the efficacy of Ã…-scale graphene nanopores in enhancing water evaporation from LiCl, NaCl, and KCl solutions, using molecular dynamics simulations. Our results demonstrate that cation-Ï€ interactions between ions and the nanoporous graphene surface play a crucial role in influencing ion populations in the nanopore vicinity, thereby leading to varied water evaporation fluxes from different salt solutions. We observe a salt type and concentration dependent evaporation flux relative to the bare liquid-vapor interface, with small-sized 4.54 Å functionalized nanopores exhibiting evaporation flux enhancements ranging from 7 to 11. Notably, for 0.6 M NaCl solutions that closely resemble seawater compositions, we observe an enhancement of 10.82. Furthermore, we find that the effectiveness of functionalized graphene nanopores in enhancing water evaporation from salt solutions significantly depends on the reduction in water-water hydrogen bond lifetimes, liquid-vapor surface tension, and free energy barrier for evaporation, achieved by placing the nanoporous graphene at the bare liquid-vapor interface. Our findings can aid in the development of sustainable solutions for desalination and separation processes, particularly in areas experiencing water scarcity.