Pressure-driven water permeation through multilayer graphene nanosheets

Abstract

Graphene‐based membranes have been shown to exhibit excellent potential in transporting water and separating ions and contaminants. The pressure‐driven water permeation through a graphene (GE) multilayer containing slit‐like gaps in each layer is investigated using molecular dynamics simulations in the present study. The effects of the driving pressure magnitude, as well as the multilayer configuration parameters including the number of GE layers, their porous ratio, the gap width and offset, the interlayer distance, and the hydrogenation of the gaps, are studied. The results show that the permeate flux is highly dependent on the number and the porous ratio of the GE layers, but is almost insensitive to the number of gaps at the same porous ratio as long as the gap width is large enough to allow water permeation. A counter‐intuitive dependence of the water flow rate on the offset distance is found that the former increases as the later increases. When the gaps are hydrogenated, the energy barrier for the water molecules entering the nanochannel is lowered, leading to much higher water flow rate across the membrane. This study is helpful for the application of GE‐based membranes for desalination and nanofiltration.

Molecular Insights into the Composition–Structure–Property Relationships of Polyamide Thin Films for Reverse Osmosis Desalination

“…Different from the nearly perfect linear increment ( R 2 > 95%) of permeance through rigid membrane structures in our previous MD studies, ,, Figures a and S3 reveal apparent fluctuations for all four compositions. The fluctuations are caused by the dynamic nature of PA structures, where deformable bonds as well as the soft van der Waals and electrostatic interactions result in the flexible and transient channels. , To examine the influence of the polymer flexibility on water transport, we immobilized the PA structure by applying a spring force (spring constant of 100 kcal mol –1 Å –2 ) on the PA atoms to their initial positions.…”

“…Different from the nearly perfect linear increment (R 2 > 95%) of permeance through rigid membrane structures in our previous MD studies, 16,18,46 Figures 6a and S3 reveal apparent fluctuations for all four compositions. The fluctuations are caused by the dynamic nature of PA structures, where deformable bonds as well as the soft van der Waals and electrostatic interactions result in the flexible and transient channels.…”

Application of Desalination Membranes to Nuclide (Cs, Sr, and Co) Separation

“…23 NF membranes are widely applied for desalination and separation of wastewater to achieve low operation pressures and high permeation fluxes. 24 Also, the RO membrane-based separation process is the key technology consistently providing clean water because of its high performance and cost efficiency. 25 In this work, we describe the NF and RO techniques using commercial membranes for application in desalination and aqueous nuclide separation.…”

Surface and structural design of nanocompounds using molecular dynamics simulations for desalination processes

“…To examine the behaviors of water molecules when being brought into contact with different surfaces at the atomic scale, various insights have been made via the approach of MD simulations. It has been found that many surface properties such as morphology and polarity can significantly influence the transport process , Kieu et al 2017. conducted MD simulations of water evaporation on a polar substrate of which the wettability can be adjusted.…”

“…Graphene, a derivative of carbon, has attracted a lot of attention over the last decade, particularly in desalination and water treatment , Kieu et al 2017, Boretti et al 2018, Dao et al 2018. The combinations of high surface area, excellent thermal conductivity and strong plasmonic potential make it a promising candidate for evaporation and steam generation.…”