The effect of chemical functional groups and salt concentration on performance of single-layer graphene membrane in water desalination process: A molecular dynamics simulation study

Abstract

In this study, the mechanisms of passing water and salt ions through nanoporous single-layer graphene membrane are simulated using classical molecular dynamics. The effects of functional groups placed in nanopores and feed water's salt concentration on water desalination are investigated. In order to understand the role of functional groups in desalination process, Methyl, Ethyl and a combination of Fluorine and Hydrogen molecules are distributed around the nanopores. In all cases, different number of functional molecules is employed in order to find an optimum distribution of the groups at hand. The results show that an appropriate distribution of Alkyl groups can properly stop the salt ions from passing through the graphene, where the flow rate of water molecules is sufficient. Moreover, the investigation of graphene membrane's performance in different salt concentrations reveals that with increase in salt concentration of feed water, the water flow rate falls and the number of salt ions on the other side of the membrane increases.