scholarly journals Efficient CH4/CO2 Gas Mixture Separation through Nanoporous Graphene Membrane Designs

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2488
Author(s):  
Naiyer Razmara ◽  
Alexsandro Kirch ◽  
Julio Romano Meneghini ◽  
Caetano Rodrigues Miranda
Keyword(s):  
Gas Separation ◽  
Interlayer Spacing ◽  
Dynamics Simulation ◽  
Two Stage ◽  
Co2 Gas ◽  
Porous Graphene ◽  
Graphene Membrane ◽  
Offset Distance ◽  
Nanoporous Graphene ◽  
Membrane Design

Nanoporous graphene membranes have drawn special attention in the gas-separation processes due to their unique structure and properties. The complexity of the physical understanding of such membrane designs restricts their widespread use for gas-separation applications. In the present study, we strive to propose promising designs to face this technical challenge. In this regard, we investigated the permeation and separation of the mixture of adsorptive gases CO2 and CH4 through a two-stage bilayer sub-nanometer porous graphene membrane design using molecular dynamics simulation. A CH4/CO2 gashouse mixture with 80 mol% CH4 composition was generated using the benchmarked force-fields and was forced to cross through the porous graphene membrane design by a constant piston velocity. Three chambers are considered to be feeding, transferring, and capturing to examine the permeation and separation of molecules under the effect of the two-stage membrane. The main objective is to investigate the multistage membrane and bilayer effect simultaneously. The permeation and separation of the CO2 and CH4 molecules while crossing through the membrane are significantly influenced by the pore offset distance (W) and the interlayer spacing (H) of the bilayer nanoporous graphene membrane. Linear configurations (W = 0 Å) and those with the offset distance of 10 Å and 20 Å were examined by varying the interlayer spacing between 8 Å, 12 Å, and 16 Å. The inline configuration with an interlayer spacing of 12 Å is the most effective design among the examined configurations in terms of optimum separation performance and high CO2 and CH4 permeability. Furthermore, increasing the interlayer distance to 16 Å results in bulk-like behavior rather than membrane-like behavior, indicating the optimum parameters for high selectivity and permeation. Our findings present an appropriate design for the effective separation of CH4/CO2 gas mixtures by testing novel nanoporous graphene configurations.

Selective Nanopores in Graphene Sheet for Separation I-129 Isotope from Air

2017 ◽  
Vol 6 (1) ◽  
pp. 10-17 ◽  
Author(s):  
Seyyed Mahmood Fatemi ◽  
Hamid Sepehrian ◽  
Masoud Arabieh
Keyword(s):  
Molecular Dynamic Simulation ◽  
Pore Size ◽  
Gas Separation ◽  
Dynamic Simulation ◽  
Separation Process ◽  
Atomic Gases ◽  
Key Factors ◽  
Graphene Membrane ◽  
Proper Size ◽  
Nanoporous Graphene

Molecular dynamic simulation was used to investigate the ability of nanoporous graphene membrane in gas separation process. Three di-atomic gases (I2, N2 and O2) were considered, in which different pore sizes were modeled on graphene. The structure contains an impermeable movable wall (piston) to push the mixture gases toward the nanoporous graphene membrane. Two different simulations were carried out, with two different piston velocities. Two key factors in gases separation process are the pore size of graphene and the velocity of movable wall. The results revealed that I-129 separation was improved by using proper size of pore and by decreasing the velocity of movable wall. It was also found that the I-129 gas radionuclides could be completely separated from nitrogen and oxygen molecules in the pore-12 graphene configuration. It was also found that nitrogen was more strongly adsorbed onto the membrane than oxygen, while I-129 was not adsorbed.

Gas Separation in Nanoporous Graphene from Molecular Dynamics Simulation

2016 ◽  
Vol 11 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Sayyed Mohammad R. Gharibzahedi ◽  
Javad Karimi-Sabet
Keyword(s):  
Molecular Dynamics ◽  
Pore Size ◽  
Gas Separation ◽  
Membrane Separation ◽  
Adsorbed Layer ◽  
Dynamics Simulation ◽  
Single Atom ◽  
Separation Performance ◽  
Separation Selectivity ◽  
Nanoporous Graphene

Abstract Membrane separation processes are energetically efficient compared to the other techniques such as cryogenic distillation and gas adsorption techniques. It is well known that a membrane's permeance is inversely proportional to its thickness. Regard to its single atom thickness and its mechanical strength, nanoporous graphene has been proposed as a very promising candidate for highly efficient gas separation applications. In this work, using classical molecular dynamics, we report the separation performance of such membrane in a molecular-sieving process as a function of pore size and chemical functionalization of pore rim. To investigate the membrane separation capability, we have calculated the permeance of each gas molecule of the considered binary mixtures through the membranes and therefore the separation selectivity. We investigated the separation performance of nanoporous graphene for CO2/N2, H2/CH4 and He/CH4 with 50:50 proportions of each component and the separation selectivity has been calculated. We also calculated the potential of the mean force to characterize the energy profile for gas transmission. The separation selectivity reduced by increasing the pore size. However, presence of chemical functionally pores in the membrane increased the separation selectivity. Furthermore, the gas permeance through nanoporous graphene membranes is related not only to transport rate to the graphene surface as well as kinetic diameters but also to molecular adsorbed layer which is formed on the surface. The flux of molecules through the nanopores is also dependent on pore chemistry which is considered as gas-pore interactions in the molecular simulations and can be a sizable factor in simulation in contrast to experimental observations. This study suggests that nanoporous graphene could represent a suitable membrane for gas separation.

scholarly journals Preparation and gas permeability of the surface-modified porous Al2O3 ceramic filter for CO2 gas separation

2013 ◽  
Vol 1 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Toshihiro Isobe ◽  
Mai Shimizu ◽  
Sachiko Matsushita ◽  
Akira Nakajima
Keyword(s):  
Gas Separation ◽  
Gas Permeability ◽  
Ceramic Filter ◽  
Co2 Gas ◽  
Al2o3 Ceramic ◽  
Surface Modified

Ultrahigh‐flux Nanoporous Graphene Membrane for Sustainable Seawater Desalination Using Low‐grade Heat

2022 ◽  
pp. 2109718
Author(s):  
Dongwei Lu ◽  
Zongyao Zhou ◽  
Zhihong Wang ◽  
Duc Tam Ho ◽  
Guan Sheng ◽  
...  
Keyword(s):  
Low Grade ◽  
Seawater Desalination ◽  
Graphene Membrane ◽  
Nanoporous Graphene ◽  
Low Grade Heat

scholarly journals Molecular Dynamics Study on the Reverse Osmosis Using Multilayer Porous Graphene Membranes

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 805 ◽  
Author(s):  
Zhongqiang Zhang ◽  
Fujian Zhang ◽  
Zhen Liu ◽  
Guanggui Cheng ◽  
Xiaodong Wang ◽  
...  
Keyword(s):  
Salt Solution ◽  
Energy Barrier ◽  
Water Flux ◽  
Solution Concentration ◽  
Water Molecules ◽  
Porous Graphene ◽  
Salt Rejection ◽  
Layer Separation ◽  
Graphene Membrane ◽  
Graphene Membranes

In this study, the reverse osmosis (RO) of a salt solution was investigated using a molecular dynamics method to explore the performance of a multilayer porous graphene membrane. The effects of the salt solution concentration, pressure, layer separation and pore offset on the RO performance of the membrane were investigated and the influences of the number of layers and the gradient structure were determined. The results show that as the salt solution concentration increases, the energy barrier of the water molecules passing through the bilayer porous graphene membranes changes slightly, indicating that the effect of the water flux on the membrane can be ignored. The salt rejection performance of the membrane improves with an increase in the concentration of the salt solution. When the pressure is increased, the energy barrier decreases, the water flux increases and the salt rejection decreases. When the layer separation of the bilayer porous graphene membrane is the same as the equilibrium spacing of the graphene membrane, the energy barrier is the lowest and the membrane water flux is the largest. The energy barrier of the bilayer porous graphene membrane increases with increasing layer separation, resulting in a decrease in the water flux of the membrane. The salt rejection increases with increasing layer separation. The water flux of the membrane decreases as the energy barrier increases with increasing pore offset and the salt rejection increases. The energy barrier effect is more pronounced for a larger number of graphene layers and the water flux of the membrane decreases because it is more difficult for the water molecules to pass through the porous graphene membrane. However, the salt rejection performance improves with the increase in the number of layers. The gradient pore structure enhances the energy barrier effect of the water molecules permeating through the membrane and the water flux of the membrane decreases. The salt rejection performance is improved by the gradient pore structure. The research results provide theoretical guidance for research on the RO performance of porous graphene membranes and the design of porous graphene membranes.

Sign in / Sign up

Export Citation Format

Share Document