Electric field assisted desalination of water using B- and N-doped-graphene sheets: A non-equilibrium molecular dynamics study

Kandezi, Maryam Kamal; Lakmehsari, Muhammad Shadman; Matta, Chérif F.

doi:10.1016/j.molliq.2020.112574

Cited by 18 publications

(3 citation statements)

References 49 publications

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“…However, the rigid structure of water molecules is kept using the SHAKE algorithm. Similar electric field values have been also incorporated in other MD papers concerning water simulations where the SHAKE algorithm is employed [58,59]. It is emphasized that this is not suggested for real applications; it only provides qualitative simulation results.…”

Section: Discussionmentioning

confidence: 99%

Molecular Dynamics Simulations of Ion Drift in Nanochannel Water Flow

2020

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The present paper employs Molecular Dynamics (MD) simulations to reveal nanoscale ion separation from water/ion flows under an external electric field in Poiseuille-like nanochannels. Ions are drifted to the sidewalls due to the effect of wall-normal applied electric fields while flowing inside the channel. Fresh water is obtained from the channel centerline, while ions are rejected near the walls, similar to the Capacitive DeIonization (CDI) principles. Parameters affecting the separation process, i.e., simulation duration, percentage of the removal, volumetric flow rate, and the length of the nanochannel incorporated, are affected by the electric field magnitude, ion correlations, and channel height. For the range of channels investigated here, an ion removal percentage near 100% is achieved in most cases in less than 20 ns for an electric field magnitude of E = 2.0 V/Å. In the nutshell, the ion drift is found satisfactory in the proposed nanoscale method, and it is exploited in a practical, small-scale system. Theoretical investigation from this work can be projected for systems at larger scales to perform fundamental yet elusive studies on water/ion separation issues at the nanoscale and, one step further, for designing real devices as well. The advantages over existing methods refer to the ease of implementation, low cost, and energy consumption, without the need to confront membrane fouling problems and complex electrode material fabrication employed in CDI.

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Section: Discussionmentioning

confidence: 99%

Molecular Dynamics Simulations of Ion Drift in Nanochannel Water Flow

2020

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“…Unlike the numerous studies on the alkali metal ions (Na and K) capture for water desalination [18][19][20][21][22][23][24][25][26][27][28], there have been relatively few studies on the capture of divalent metal ions (Ca and Mg) by graphene [5,[29][30][31][32][33][34]. Malhotraa et al [33] investigated the adsorption of several ions (Pb, As, Cu, Zn, Cr, Hg, Ni, Cd, Ca, Li, Fe) on pristine graphene by both experiments and density functional theory (DFT) calculations.…”

Section: Introductionmentioning

confidence: 99%

Understanding adsorption of divalent metals ions (Mg, Ca) on Nitrogen-, Boron- doped, and defective graphene in nanofiltration process using van der Waals density functional method

Tan Thi,

Vuong,

Van Le

et al. 2023

Mater. Res. Express

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Removal of divalent metal ions (Mg and Ca) by graphene membrane has a great implication for manufacturing chitin and chitosan in filtration process. Despite its importance, influences of the doping and vacancy in graphene on the adsorption of those metal ions remain unclear. Here, we study the adsorption of those metal ions on several graphene surfaces, namely pristine graphene (Gra), graphitic N- and B- doped graphene (N- and B-Gra), monovacancy graphene (MV-Gra), monovacancy graphene functionalized by an epoxy (O-MV-Gra), and monovacancy graphene func- tionalized by an hydroxyl group (OH-MV-Gra) by van der Waals density functional (vdW-DF) method. It was found all considered graphene surfaces have strong interactions with Ca, whereas Mg only chemisorbs on MV-Gra and B-Gra. Energetically, comparing with Ca adosprtion on pris- tine graphene, both B doping and vacancy creation strengthen the Ca adsorption, while N doping slight decreases it. The electronic structure analysis uncovers enhancement of the Ca–graphene interaction by B doping and vacancy formation. Because of the results that have been observed, the removal of Ca ions from aqueous solution can be enhanced by the creation of nanopore or B doping in graphene, in which Ca atom are strongly captured by graphene.

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“…The range of the electric field strength we adopted has also been used in some simulation research [31,[34][35][36]. Water molecules are chosen as the TIP3P water model, which is mostly adopted to investigate water properties in a nanochannel especially under the influence of an electric field recently [35][36][37][38][39][40][41]. The carbon atoms are modeled as uncharged Lennard-Jones (LJ) particles with a cross-section of σ CC = 0.34 nm, σ CO = 0.3275 nm, and a depth of the potential well of ε CC = 0.3612 kJ/mol, ε CO = 0.4802 kJ/mol [42].…”

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confidence: 99%

Reinforcing a water bridge in a disjoint nanochannel

Meng¹,

Li²,

Shen³

et al. 2020

EPL

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Understanding and controlling water molecules confined in water channels has great applications. Many artificial water channels have been designed to mimic water permeation across water channels. One kind of artificial water channels, which contains two disjoint carbon nanotubes that are not physically connected has attracted much attention. Water transfers through the disjoint nanochannel by a water bridge. However, the water bridge is affected by the nanogap between two disjoint carbon nanotubes. Here, we firstly report on the possibility of reinforcing a water bridge in a disjoint nanochannel by molecular dynamics simulations and find that the length of the nanogap, the electric field strength, the direction of the electric field and the effective pressure within water have an effect on the formation of a water bridge in the disjoint nanochannel. The analysis of the Lennard-Jones potential and the potential of mean force helps to reveal the mechanism. Our findings are beneficial for designing nanodevices with disjoint nanostructures and understanding the effects of the nanogap on the behaviors of water molecules in the disjoint nanochannel.

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Electric field assisted desalination of water using B- and N-doped-graphene sheets: A non-equilibrium molecular dynamics study

Cited by 18 publications

References 49 publications

Molecular Dynamics Simulations of Ion Drift in Nanochannel Water Flow

Molecular Dynamics Simulations of Ion Drift in Nanochannel Water Flow

Understanding adsorption of divalent metals ions (Mg, Ca) on Nitrogen-, Boron- doped, and defective graphene in nanofiltration process using van der Waals density functional method

Reinforcing a water bridge in a disjoint nanochannel

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