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A. S. Kazemi and M. A. Abdol
stops 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 revealed that with an 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 [107]. The desalination performances simulated
for monolayer graphene nanopores with pyridinic N doped functionalization under
various N-doping levels in [108] demonstrated that all N-doped graphene membranes
exhibit higher water flux with several orders of magnitude higher than polymeric RO
membranes and high salt rejections. Further simulations of the PMF profiles showed a
moderate free energy barrier for water and large free energy barrier for ions. The interfacial properties of water and ions, as well as their free energy landscapes in passing
through the graphene nanopores, were simulated to explore the desalination mechanism. Density Functional Theory (DFT) simulations revealed that the salt rejection
mechanism of the functionalized graphene was the pore size exclusion of hydrated
ions and the charged repulsion from pore surfaces was not the main factor [108].
(b) Simulation considerations and summary
Figure 5 shows a snapshot of a typical MD simulation box in various reports. The
model graphene sheet membrane (L x Å × L y Å), with a pore in its center, is placed
parallel to the xy plane in the center of the simulation box. The pore diameter
(R) is a few angstroms and is obtained by removing carbon atoms, as necessary.
The membrane is surrounded by L z1 and L z2 Å of water along the z-direction on
both sides. Different functional groups are schematically added adjacent to the pore.
Fig. 5 Snapshot of a typical MD simulation box in various reports. L x and L y are the dimensions
of the graphene sheet, with a pore in its center with a diameter R. The sheet is placed parallel to the
xy plane and is surrounded by L z1 and L z2 Å of water along the z-direction on both sides. Different
functional groups are schematically added adjacent to the graphene pore
A. S. Kazemi and M. A. Abdol
stops 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 revealed that with an 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 [107]. The desalination performances simulated
for monolayer graphene nanopores with pyridinic N doped functionalization under
various N-doping levels in [108] demonstrated that all N-doped graphene membranes
exhibit higher water flux with several orders of magnitude higher than polymeric RO
membranes and high salt rejections. Further simulations of the PMF profiles showed a
moderate free energy barrier for water and large free energy barrier for ions. The interfacial properties of water and ions, as well as their free energy landscapes in passing
through the graphene nanopores, were simulated to explore the desalination mechanism. Density Functional Theory (DFT) simulations revealed that the salt rejection
mechanism of the functionalized graphene was the pore size exclusion of hydrated
ions and the charged repulsion from pore surfaces was not the main factor [108].
(b) Simulation considerations and summary
Figure 5 shows a snapshot of a typical MD simulation box in various reports. The
model graphene sheet membrane (L x Å × L y Å), with a pore in its center, is placed
parallel to the xy plane in the center of the simulation box. The pore diameter
(R) is a few angstroms and is obtained by removing carbon atoms, as necessary.
The membrane is surrounded by L z1 and L z2 Å of water along the z-direction on
both sides. Different functional groups are schematically added adjacent to the pore.
Fig. 5 Snapshot of a typical MD simulation box in various reports. L x and L y are the dimensions
of the graphene sheet, with a pore in its center with a diameter R. The sheet is placed parallel to the
xy plane and is surrounded by L z1 and L z2 Å of water along the z-direction on both sides. Different
functional groups are schematically added adjacent to the graphene pore