Molecular dynamics investigation on seawater desalination mechanism driven by external pressure through porous graphene membranes

The seawater desalination through porous graphene membrane is considered as promising candidate technology for water purification, but the desalination mechanism is seldom concerned at nanoscale. In this study, the microstructures of pressure driven seawater desalination based on porous graphene membrane was established, and the desalination performance was studied by means of molecular dynamics simulations. Based on the observed dynamic evolution of the water molecules transportation behaviors and microstructures, the salt rejection and water permeation mechanism were proposed. The effects of graphene pore diameter, external pressure and temperature on the desalination performance were investigated. The results indicate that the water flux can be increased by 67.20% when the external pressure increases from 100 MPa to 200 MPa. Under the external pressure of 300 MPa, when the diameter of graphene pore increased from 1 nm to 2 nm and 3 nm, the number of filtered water molecule is increased by 48.83% and 67.33%, respectively. The filtered water molecules can be increased by 4.06% with the increase of temperature from 300 K to 360 K. The possible desalination mechanism was explored and revealed by us, which is expected to be helpful for efficient seawater desalination.

Automated summary

This study establishes the microstructures of pressure-driven seawater desalination based on a porous graphene membrane and investigates its desalination performance through molecular dynamics simulations. The results show that the desalination efficiency can be improved by increasing the external pressure, graphene pore diameter, and temperature.