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.

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.

scholarly journals Mixed Matrix Membrane Performance Prediction for Gas Separation using Modified Models

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
A. Salimi ◽  
O. Bakhtiari ◽  
M. K. Moghaddam ◽  
T. Mohammadi
Keyword(s):  
Gas Separation ◽  
Molecular Sieves ◽  
Molecular Sieve ◽  
Membrane Separation ◽  
Maxwell Model ◽  
Industrial Applications ◽  
Mixed Matrix Membrane ◽  
Separation Performance ◽  
Mixed Matrix ◽  
Two Parameters

Gas separation using membrane processes are potentially economical in industrial scale. Two parameters are used for analyzing the membrane separation performance: permeability and selectivity. There is a trade off between them for polymeric membranes that makes it impossible to increase both of them simultaneously. Molecular sieve membranes, on the other hand, exhibit high permeability and selectivity but are brittle in nature and costly. A new generation of membranes has made many hopes to use simultaneously both desired properties of polymers and molecular sieves in a structure called “mixed matrix membrane (MMM)” where a molecular sieve is incorporated within a polymer matrix. As other branches of science and engineering, having a tool to predict MMMs performance seems to be essential to save time and money for research and industrial applications. Many mathematical models were developed to predict MMMs performance based on separation performance of fillers and polymers. Maxwell model is the simplest model developed for prediction of electrical properties of composite materials but it is not perfect for all cases. Some modifications were performed on Maxwell model and some other modified models were developed for better prediction of MMMs separation performance. In this research, modified Maxwell and Bruggeman models were employed to predict gas separation performance of some MMMs in the current work and the results were acceptable for all non–ideal cases which might be occurred in MMMs structure.

Mechanical properties of Ge/Si core-shell nanowires under a uniaxial tension

2006 ◽  
Vol 958 ◽  
Author(s):  
Y. Yano ◽  
T. Nakajima ◽  
K. Shintani
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Single Atom ◽  
Core Shell ◽  
The Core ◽  
Young’S Moduli ◽  
Vegard’S Law ◽  
Shell Nanowires

ABSTRACTThe mechanical properties of Si/Ge core-shell nanowires under a unixial tension are studied using molecular-dynamics simulation. The effects of anisotropy and the fraction of the core atoms on the Young's moduli of the core-shell nanowires are examined. The values of their Young's moduli deviate from those calculated using Vegard's law. Single atom chains are formed at the final stages of elongation of the nanowires.

scholarly journals The prospect of synthesis of PES/PEG blend membranes using blend NMP/DMF for CO2/N2 separation

2021 ◽  
Vol 28 (5) ◽  
Author(s):  
Fadel Abdul Hadi Juber ◽  
Zeinab Abbas Jawad ◽  
Bridgid Lai Fui Chin ◽  
Swee Pin Yeap ◽  
Thiam Leng Chew
Keyword(s):  
Gas Separation ◽  
Carbon Capture ◽  
Membrane Separation ◽  
Carbon Capture And Storage ◽  
Polymeric Membranes ◽  
Polymeric Membrane ◽  
Mixed Matrix Membranes ◽  
Separation Performance ◽  
Trade Off ◽  
Blend Membranes

AbstractCarbon dioxide (CO2) emissions have been the root cause for anthropogenic climate change. Decarbonisation strategies, particularly carbon capture and storage (CCS) are crucial for mitigating the risk of global warming. Among all current CO2 separation technologies, membrane separation has the biggest potential for CCS as it is inexpensive, highly efficient, and simple to operate. Polymeric membranes are the preferred choice for the gas separation industry due to simpler methods of fabrication and lower costs compared to inorganic or mixed matrix membranes (MMMs). However, plasticisation and upper-bound trade-off between selectivity and permeability has limited the gas separation performance of polymeric membranes. Recently, researchers have found that the blending of glassy and rubbery polymers can effectively minimise trade-off between selectivity and permeability. Glassy poly(ethersulfone) (PES) and rubbery poly(ethylene) glycol (PEG) are polymers that are known to have a high affinity towards CO2. In this paper, PEG and PES are reviewed as potential polymer blend that can yield a final membrane with high CO2 permeance and CO2/nitrogen (N2) selectivity. Gas separation properties can be enhanced by using different solvents in the phase-inversion process. N-Methyl-2-Pyrrolidone (NMP) and Dimethylformamide (DMF) are common industrial solvents used for membrane fabrication. Both NMP and DMF are reviewed as prospective solvent blend that can improve the morphology and separation properties of PES/PEG blend membranes due to their effects on the membrane structure which increases permeation as well as selectivity. Thus, a PES/PEG blend polymeric membrane fabricated using NMP and DMF solvents is believed to be a major prospect for CO2/N2 gas separation.

Investigation of the silica pore size effect on the performance of polysulfone (PSf) mixed matrix membranes (MMMs) for gas separation

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Gholamhossein Vatankhah ◽  
Babak Aminshahidy
Keyword(s):  
Mesoporous Silica ◽  
Pore Size ◽  
Gas Separation ◽  
Gas Permeation ◽  
Mixed Matrix Membranes ◽  
Separation Performance ◽  
Mixed Matrix ◽  
Small Pore ◽  
Mcm 41 ◽  
Matrix Membranes

Abstract MCM-41 and SBA-15 mesoporous silica materials with different pore sizes (3.08 nm for small pore size MCM-41 (P 1), 5.89 nm for medium pore size SBA-15 (P 2), and 7.81 nm for large pore size SBA-15 (P 3)) were synthesized by the hydrothermal method and then functionalized with 3-aminopropyltrietoxysilane by postsynthesis treatments. Next, polysulfone-mesoporous silica mixed matrix membranes (MMMs) were prepared by the solution casting method. The obtained materials and MMMs were characterized by various techniques including X-ray diffraction, scanning electron microscopy, and N2 adsorption-desorption, and Brunauer-Emmett-Teller method to examine the crystallinity, morphology, and particle size, pore volume, specific surface area, and pore size distribution, respectively. Finally, the gas permeation rates of prepared MMMs were measured in 8 bar and 25 °C and the effect of pore size of modified and unmodified mesoporous silica on the gas separation performance of these MMMs were investigated. The experimental results indicate that the carbon dioxide (CO2) and methane (CH4) permeability and CO2/CH4 selectivity were increased with an enhancement in the particle pore size.

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