Fast evaporation of ultra-thin pure and saline water film through functionalized holey graphene membrane

Water evaporation confined in nanoscale is a ubiquitous phenomenon in nature, which has a crucial importance in a broad range of technical applications. In this work, the evaporation of the ultra-thin liquid film confined below the graphene nanopore is simulated with MD approach, and the influences of the functional group and ion concentration on the evaporation process are analyzed based on the obtained data. It is found that the modifi-cation with hydroxyl functional groups on the graphene nanoporous membrane can enhance the heat transfer between solid and liquid, and the electrostatic interaction breaks the ordered hydrogen bond network among water molecules, thus the evaporation rate can be improved accordingly. For the electrolytic solution at a higher ion concentration, the oxidized-pore nanoporous membrane has an evaporation deterioration due to the ion aggregation effect, which results in a decreasing equilibrium temperature of water molecules. There exists one optimal ion concentration that can realize the highest evaporation rate. It is found the rotational and trans-lational inertias of the ions are the main factors affecting the evaporation rate of electrolytic solution under the hydroxyl group functionalized graphene nanoporous membrane.

Automated summary

In this study, the evaporation of an ultra-thin liquid film confined below a graphene nanopore was simulated using a molecular dynamics (MD) approach. The effects of functional groups and ion concentration on the evaporation process were analyzed based on the obtained data. It was found that the modification with hydroxyl functional groups on the graphene nanoporous membrane can enhance heat transfer and improve the evaporation rate. However, for electrolytic solutions with higher ion concentration, the oxidized-pore nanoporous membrane exhibits evaporation deterioration due to the ion aggregation effect, resulting in a decrease in the equilibrium temperature of water molecules. There exists an optimal ion concentration that maximizes the evaporation rate. The rotational and translational inertias of the ions were identified as the main factors affecting the evaporation rate of electrolytic solutions under the hydroxyl group functionalized graphene nanoporous membrane.