Saltwater transport through pristine and positively charged graphene membranes

Nguyen, Chinh Thanh; Beşkök, Ali

doi:10.1063/1.5032207

Cited by 18 publications

(14 citation statements)

References 55 publications

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“…It is observed that the local number density fluctuates near the NPGM, which is commonly known as density layering. This has been reported by many other researchers in MD simulations of nanofluidic flows 32,39,46,48,63 and has been authenticated experimentally. 64−66 This density layering diminishes at an approximately 3σ C−Ar distance from the NPGM, consistent with other researchers' findings.…”

Section: ■ Results and Discussionsupporting

confidence: 71%

“…This phenomenon happens for both side reservoirs, which has also been confirmed by other researchers. 39,43,69,70 The bulk pressure (P bulk ) of each side of the membrane was calculated by averaging the local pressures in the bulk region. The bulk pressure drop (ΔP bulk ) was obtained by…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…On the other hand, pressure drops maintain a proportional relationship with flow rates, which has been confirmed in previous studies. 32,39,58,72 So, if the flow rates for various pore sizes are approximately equal, then it is acceptable to continue the investigation. The flow rates obtained from MD simulation have a slight upward trend and do not vary significantly with the changing pore diameter.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Scale Effect on Simple Liquid Transport through a Nanoporous Graphene Membrane

Hossain

Kim

2021

Langmuir

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The transport mechanism of a simple liquid through nanoporous graphene membranes (NPGMs) with pores of various diameters has been explored by utilizing nonequilibrium molecular dynamics (NEMD) simulation. The flow is initiated using a pressure-driven flow mechanism that moves the specular reflection wall at a constant velocity. Both the local density peak near the membrane and the pressure drop are dependent on the pore diameter. For accurate calculation of the velocity profile inside the nanopore, we implemented three boundary approaches and local nanoscale variants to see the effect of these factors on the nature of the nanoscale flow. We found an optimized definition of the pore boundary, which minimizes the deviation between MD results and slip-viscosity-modified Sampson’s prediction for nanopores of various diameters. Additionally, we observed that with decreasing pore size, the pore center velocity increases, as does the slip velocity, which we attributed to van der Waals interaction between the liquid and wall atoms inside the nanopore. However, the effects of slip velocity, interfacial viscosity, and pore boundary decay exponentially with increasing pore diameter because of the dominance of van der Waals repulsive forces at the molecular level.

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Section: ■ Results and Discussionsupporting

confidence: 71%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

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Scale Effect on Simple Liquid Transport through a Nanoporous Graphene Membrane

Hossain

Kim

2021

Langmuir

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“…1(c). The method has been widely used [7][8][9][10][11][12]. The shear-driven and force-driven flows are enabled by setting the wall a velocity of 50 nm/ns and by setting gravity of 49 m/s 2 .…”

Section: Simulation Model and Theoretical Backgroundmentioning

confidence: 99%

Viscous heating and temperature profiles of liquid water flows in copper nanochannel

Dinh

Kim

2019

J Mech Sci Technol

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Understanding nanoscale fluidic transport becomes increasingly important due to the rapid development of nanotechnology and nanofabrication. By using molecular dynamics (MD) simulations, we investigated the viscous heating of water flows in copper nanochannels. The two scenarios that were studied are Couette flows and Poiseuille flows. We observed the scale effects on the distribution of fluid density, streaming velocity, fluid viscosity, and temperature across the channel. The results revealed the significant effects of surface forces on causing a large deviation between simulation results and classical hypothesis. We found that the energy equation coupled with the thermal-slip boundary conditions still fails to predict the temperature distributions. Hereby, further scale effects are taken into account, which leads to better predictions. The model that we developed in this study shows the relative deviation to the simulation data within 5 %, which is small compared to the conventional continuum approach (i.e., up to 51 %).

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“…Liquid transport in nanoscale confinements is of great importance in various applications, ranging from drug delivery 1 to water desalination [2][3][4][5] and biosensing. 6 As the size of a conduit decreases down to the nanoscale, interfacial phenomena between liquid molecules and wall atoms become prominent, which leads to deviations from classical no-slip boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

The role of water models on the prediction of slip length of water in graphene nanochannels

Celebi

Nguyen

Hartkamp

et al. 2019

The Journal of Chemical Physics

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Slip lengths reported from molecular dynamics (MD) simulations of water flow in graphene nanochannels show significant scatter in the literature. These discrepancies are in part due to the used water models. We demonstrate self-consistent comparisons of slip characteristics between the SPC, SPC/E, SPC/Fw, TIP3P, TIP4P, and TIP4P/2005 water models. The slip lengths are inferred using an analytical model that employs the shear viscosity of water and channel average velocities obtained from nonequilibrium MD simulations. First, viscosities for each water model are quantified using MD simulations of counterflowing, force-driven flows in periodic domains in the absence of physical walls. While the TIP4P/2005 model predicts water viscosity at the specified thermodynamic state with 1.7% error, the predictions of SPC/Fw and SPC/E models exhibit 13.9% and 23.1% deviations, respectively. Water viscosities obtained from SPC, TIP4P, and TIP3P models show larger deviations. Next, force-driven water flows in rigid (cold) and thermally vibrating (thermal) graphene nanochannels are simulated, resulting in pluglike velocity profiles. Large differences in the flow velocities are observed depending on the used water model and to a lesser extent on the choice of rigid vs thermal walls. Depending on the water model, the slip length of water on cold graphene walls varied between 34.2 nm and 62.9 nm, while the slip lengths of water on thermal graphene walls varied in the range of 38.1 nm-84.3 nm.

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Saltwater transport through pristine and positively charged graphene membranes

Cited by 18 publications

References 55 publications

Scale Effect on Simple Liquid Transport through a Nanoporous Graphene Membrane

Scale Effect on Simple Liquid Transport through a Nanoporous Graphene Membrane

Viscous heating and temperature profiles of liquid water flows in copper nanochannel

The role of water models on the prediction of slip length of water in graphene nanochannels

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