Atomistic understanding on desalination performance of pristine graphenylene nanosheet membrane at high applied pressures.

Molecular dynamics (MD) simulations are conducted to assess pristine graphenylene membranes' effectiveness in seawater desalination, explicitly focusing on their salt rejection and water permeability capabilities. This study investigates the potential of the graphenylene for separation of the Na+ as monovalent cation, in order to evaluate its further application for separation of the other type of contaminants. To this end, the pristine graphenylene nanosheet is introduced into the simulation box which included the water molecules, sodium and chlorine ions. Subsequently, MD simulations were conducted by applying different amounts of external pressures in which the temperature changes are investigated as another effective parameter in water permeability and salt rejection properties. Furthermore, the water density map, radial distribution functions, and water density elucidate the performance of the considered membrane in the presence of water molecules, Na+ ions, and Cl- ions. The optimum performance of the pristine graphenylene for seawater desalination is achieved at P = 400 MPa and T = 298 K that results in the water flux of 2920 L/m2 h bar and 98.8 % salt rejection. The pristine graphenylene nanosheet shows significant potential in effectively separating salt ions, which has elucidated its importance and subsequently, the functionalized membrane for this application.

Atomistic understanding of Ti3C2 MXene membrane performance for separation of nitrate ions from aqueous solutions.

Water desalination, which is a reliable method for providing drinking water and a suitable solution, as well as the membrane filtration method in wastewater treatment, has increased significantly in recent years. In this research, the separation of nitrite and nitrate ions from aqueous solutions was done using the MXene membrane of the Ti3C2 type using molecular dynamics simulation. In this study, various parameters, such as pore size MXene structure, characteristics of cavities, applied pressure, and flux were investigated. To investigate the removal of toxic pollutants from water, water flux, potential mean force, distribution of water molecules, and density were investigated. The results showed that the amount of penetration through the membrane increased with the increase in pressure. It was observed that by applying pressure to the system, the number of water molecules accumulated in front of the membrane decreases because they quickly pass through the membrane, which indicates the positive effect of increasing pressure on the separation rate of molecules. The permeability of this membrane was several times higher than the existing membranes in the industry. So that Mexene membranes, which consist of at least two layers, can repel ions with 100 % success.

Understanding the performance of RHO type zeolite membrane for CH4/N2 separation based on molecular dynamics and deep neural network methods.

This study shows a molecular dynamics (MD) simulation study on the performance of the RHO zeolite membrane for separating nitrogen from methane/nitrogen gas mixtures. The contamination of natural gas, predominantly composed of methane, with nitrogen diminishes its value. Zeolite membranes offer promising prospects for gas separation due to their stability, rigid pore structure, and molecular sieving properties. The study investigates the impact of pressure difference (up to 30 MPa), feed composition, and membrane thickness on the separation rate at a system temperature of 298 K. Results demonstrate that the RHO zeolite membrane exhibits high permeability and selectivity for N2 separation, surpassing the upper limit defined by Robson with a maximum permeability of 2.14 × 105 GPU (Gas Permeation Units). Exceptional selectivity of N2 over CH4 molecules is observed. Additionally, altering the feed composition and membrane thickness positively influences the membrane's separation performance, thereby enhancing its efficiency. The findings contribute to the advancement of separation technologies, providing valuable insights into the potential application of zeolite membranes for efficient N2 separation from CH4/N2 gas mixtures in natural gas processing. Furthermore, the study explores the use of Deep Neural Network (DNN) models to predict the membrane's performance under diverse operating conditions. The DNN models, trained using simulation data from MD simulations, exhibit high accuracy with a coefficient of determination (R2) exceeding 0.9, ensuring reliable predictions. The integration of DNN models facilitates the optimization of zeolite membrane-based gas separation systems, improving their design and operation.

A computational investigation of DMSO/water separation through functionalized GO multilayer nanosheet membrane using molecular dynamics simulation and deep neural network model for membrane performance prediction.

In this molecular dynamics (MD) simulation study, the separation of dimethyl sulfoxide (DMSO) from water was investigated using multilayer functionalized graphene oxide (GO) membranes. The GO nanosheets were modified with chemical groups (-F, -H) to alter their properties. The study analyzed the influence of pressure and functional groups on the separation rate. Additionally, a deep neural network (DNN) model was developed to predict membrane behavior under different conditions in water treatment processes. Results revealed that the fluorine-functionalized membrane exhibited higher permeation compared to the hydrogen-functionalized one, with potential of mean force (PMF) analysis indicating higher energy barriers for water molecules passing through the hydrogen-functionalized membrane. The study used density profile, water density map analysis, and radial distribution function (RDF) analysis to understand water and DMSO molecule interactions. The diffusion coefficient of water molecules was also calculated, showing higher diffusion in the fluorine-functionalized system. Overall, the findings suggest that functionalized GO membranes are effective for DMSO-water separation, with the fluorine-functionalized membrane showing superior performance. The DNN model accurately predicts membrane behavior, contributing to the optimization of membrane separation systems.

A comparative study on penetration mechanisms of drug-loaded carbon and boron nitride nanotubes through biological membranes by steered molecular dynamics simulations.

Understanding the mechanism by which nanotubes penetrate cell membranes is challenging from multiple perspectives. As a drug delivery system, boron nitride nanotubes (BNNTs) have a similar structure to carbon nanotubes but with B-N bonds instead of C-C bonds. Through a remarkable series of direct and indirect observations within specific cells, these nanotubes are popularly attributed as superior penetrant into cell membrane. Suitable functional groups and polymers are often needed to enhance the biocompatibility and solubility of BNNTs and CNTs in biological media. In addition, to figure out the effect of functional groups, the nanostructures without functional groups were first examined together with their anticancer drugs (fluorouracil and letrozole). All partial charges of the drug and nanotube have been investigated through population analysis. After that, with a total of 40 simulations (MD and SMD simulations), various analytical techniques were employed to examine the interaction between drugs and nanotubes with POPE, which is a class of phospholipids existing in biological membrane, in aqueous media. Noteworthy among these techniques is the mean-squared displacement analysis to compare the diffusion rate of nanocarriers and the radial distribution function analysis, which was utilized to compare water concentrations surrounding nanotubes. Additionally, the stability of the drug within the nanotube was assessed through mass center distance analysis. The diffusion coefficients of the nanotube-membrane complex were compared against various chemical agents by employing mean squared displacement analysis. The findings of the study revealed that the tethering of tetra ethylene glycol results in the augmentation of the water molecules surrounding the nanotubes while simultaneously enhancing the durability of the drug being conveyed. Nonetheless, the addition of tetra ethylene glycol resulted in a reduction in the nanocarrier's diffusion coefficient.Communicated by Ramaswamy H. Sarma.

Highly efficient helium purification through a dual-membrane system: insights from molecular dynamics simulations.

Almost all helium is resourced from natural gas reservoirs. Hence, it is essential to develop new efficient technologies to recover helium from natural gas. In this work, we propose a novel dual membrane system, consisting of C2N (M1) and graphdiyne (M2) membranes, to separate and purify helium from a ternary gas mixture of He/N2/CH4. In this regard, we performed molecular dynamics (MD) simulations to investigate the separation performance of the proposed system. Here, we explored the effect of applied pressure (up to 2 MPa) and the feed composition on the separation performance. The simulation results revealed that in the designed system, the M1 membrane allows He and N2 to diffuse through and prevents CH4 from crossing even at an applied pressure gradient. Next, the M2 membrane only allows He to transfer through and prevents N2 from crossing even at the applied pressure gradient. As a result, the dual membrane system showed a high He permeance of 2.5 × 106 GPU and ultrahigh He selectivity. In addition, the suggested dual membrane system could separate three components simultaneously at the applied pressure of 2 MPa, which implies the outstanding performance of the system. We also analyzed the density map, the van der Waals interactions, and the potential of the mean force calculations to better understand the permeation of gas species across the designed system.

Understanding the performance of graphdiyne membrane for the separation of nitrate ions from aqueous solution at the atomistic scale.

A molecular dynamics simulation study is conducted to investigate the capability of the pristine graphdiyne nanosheet for nitrate ion separation from water. The removal of nitrate ion contaminants from water is of critical importance as it represents an environmental hazard. The graphdiyne is a carbon-based membrane with pore density of 2.4 × 1018 pores/m2 and incircle radius of 2.8 Å. We show that the efficient water flow is accurately controlled through fine regulation of the exerted hydrostatic pressure. The high water permeability of 6.19 L.Day-1cm-2MPa-1 with 100% nitrate ions rejection suggests that the graphdiyne can perform as a suitable membrane for nitrate separation. The potential of mean force analysis of the single water molecule and nitrate ion indicated the free energy barriers for nitrate of about 4 times higher than that of water molecules. The results reveal the weak interaction of the water molecules and the membrane which aid to high water flux.

Efficient separation of He/CH4 mixture by functionalized graphenylene membranes: A theoretical study.

In this work, we prepared two types of functionalized pore on pristine graphenylene membrane to study and compare the He/CH4 separation performance employing molecular dynamics (MD) simulation. The gas molecules transport through the membranes was monitored during the simulations. The results indicated that methane molecules cannot pass through the membranes under applied conditions, while helium molecules simply penetrate through, which verifies the ultrahigh selectivity of helium over methane molecules. The maximum helium permeance of about 1 × 107 GPU was obtained through the functionalized graphenylene membrane at room temperature, which is much higher than graphenylene membrane. As a consequence, the functionalized graphenylene membrane can supply both high permeance and selectivity for helium separation. The van der Waals (vdW) interactions between gas molecules and the surface of the membrane was also investigated. We further conducted the potential of mean force (PMF) calculations to study the permeation of gas molecules across the membrane. Although methane molecules, due to more powerful interactions between them and the surface of the membrane, adsorb on the membrane surface, face higher energy barrier near the membrane nanopore. In reality, adsorption prefers methane molecules on the membrane surface, while diffusion favors helium over methane molecules through the nanopores. The functionalized graphenylene membrane is expected to be able to be employed as a promising membrane for a highly efficient helium purification system.

A theoretical investigation into the effects of functionalized graphene nanosheets on dimethyl sulfoxide separation.

The potential of carbon-based nanosheet membranes with functionalized pores is great as water treatment membranes. Using the molecular dynamic simulation technique, the dimethyl sulfoxide (DMSO) separation from the water/DMSO binary solution is investigated, and the functionalized graphene nanosheets are used as a membrane. This membrane was functionalized by -F (fluorine) and -H (hydrogen) functional groups. For the separation of DMSO, external hydrostatic pressures up to 100 MPa were applied to the considered systems. The separation mechanism was based on molecular size. Multiple analyses were done to study the capability of considered membranes for the separation of DMSO molecules from water. The simulation results have indicated that the graphene membrane with various functional groups was impervious to DMSO molecules, and the water molecules were able to permeate across the membrane's pore with high penetrability. In this regard, the water permeability in 100 MPa was obtained at 3915.5 and 3715.3 L m-2. h-1. bar-1 for fluorinated and hydrogenated pore membranes, respectively. These functionalized graphene membranes have high efficiency, and they can be considered effective modules for water/DMSO binary mixture separations.

Efficient water desalination through mono and bilayer carbon nitride nanosheet membranes: Insights from molecular dynamics simulation.

Water desalination through membranes is an excellent way to access drinking water. Among two-dimensional nanosheet membranes for water desalination, carbon nitride (C2N) nanosheet has been considered as a promising membrane by researchers because of its inherent structure and mechanical strength. In this work, molecular simulations were used to study the efficiency of the pristine C2N nanosheet in the water desalination process using applied hydrostatic pressure to the system. In our simulation box, the C2N nanosheet was placed in the center of the simulation cell in an aqueous ionic solution. Due to the applied pressure to the system, water molecules overcame the forces that prevented them from passing through the C2N, and therefore, they passed through the C2N membrane. The water flux and water permeability of considered systems were obtained. Also, for more investigation, water density, radial distribution function of ions, the water density map, and hydrogen bonds of the system were conducted. The results demonstrated that the C2N membrane is an effective membrane for desalination even at low pressures with the acceptable water flux and salt rejection.

Efficient Removal of Heavy Metals from Aqueous Solutions through Functionalized γ-Graphyne-1 Membranes under External Uniform Electric Fields: Insights from Molecular Dynamics Simulations.

Carbon-based nanosheet membranes with functionalized pores have great potential as water treatment membranes. In this study, the separation of Hg2+ and Cu2+ as heavy metal ions from aqueous solutions using a functionalized γ-graphyne-1 nanosheet membrane is investigated by molecular dynamics simulations. The simulation systems consist of a γ-graphyne-1 nanosheet with -COOH or -NH2 functional groups on the edge of pores placed in an aqueous solution containing CuCl2 and HgCl2. An external electric field is applied as a driving force across the membrane for the separation of heavy metal ions using these functionalized pores. The ion-membrane and water molecule-membrane interaction energies, the radial distribution function of cations, the retention time and permeation of ions through the membrane, the density profile of water and ions, and the hydrogen bond in the system are investigated, and these results reveal that the performance of -NH2-functionalized γ-graphyne-1 is better than that of -COOH-functionalized γ-graphyne-1 in the separation of Cu2+, while the Hg2+ cations encounter a high energy barrier as they pass through the membrane, especially in the -COOH-functionalized pore, due to their larger ionic radius and the smaller pore size of this membrane.

Molecular insights into water desalination performance of pristine graphdiyne nanosheet membrane.

Desalination is an exciting technology to solve the global water problem. In recent years, the graphyne-based membranes have been paid much attention to water purification, because of their high resistance and efficiency, as well as low production cost. Herein, the molecular simulations were done to investigate the salt rejection from aqueous solution through the pristine graphdiyne (graphyne-2) nanosheet. For this purpose, a simulation cell including an aqueous solution of sodium and chloride ions and a graphdiyne membrane has been considered. For ion rejection from aqueous solution, a range of hydrostatic pressures was applied to the box. The water density, radial distribution function, and water density map analysis were studied to investigate the structure of water molecules in different parts of the simulation box including the feed side and the pure water side. The results demonstrated that the graphdiyne membrane has 100% salt rejection at pressures <400 MPa, and its permeability is higher than conventional polymeric membranes.

Molecular Dynamics Simulation Study of the HIV-1 Protease Inhibit ion Using Fullerene and New Fullerene Derivatives of Carbon Nanostructures.

BACKGROUND: The water insolubility of fullerene C60 nanostructure greatly hampers its biological applications as an effective HIV-1 protease inhibitor, which suggests to synthesis new C60 derivatives with different functional polar groups. METHOD: The new carbon nanostructures of fulleropyrrolidines with one and two polar acetoxyhydroxyl (AcH) groups (C60-A and C60-B, respectively) were constructed to evaluate their interactions and binding affinity into HIV-1 protease active site via theoretical molecular docking and molecular dynamic simulations. Data obviously indicated the higher affinity of fulleropyrrolidines derivatives C60-A and C60-B compared to fullerene C60 in interacting with HIV-1 protease active site cavity. The functional groups in C60 caused better residing of C60 derivatives in the center of active site by changing the spherical shape of C60, constructing different stable H-bonds with supporting the main π interactions between C60 and aromatic Phe53/Arg8 in protease active site. Our finding showed that the functionalization of C60 is essential for both increasing solubility and improving different π interactions of C60 with protease. Also, H-bond forming with AcH functional groups and enzyme active site residues is more important to support the van der Waals interactions between C60 fragment of fulleropyrrolidines and enzyme cavity. Since enzyme possesses aspartic acid residues in active site, C60-B with two AcH groups interacted with the active site more efficiently via additional H-bond relative to C60-A. RESULTS: Finally, the results indicate a possible use of the investigated fulleropyrrolidines derivatives as new HIV-1 protease inhibitors.

Molecular dynamics simulation of salt rejection through silicon carbide nanotubes as a nanostructure membrane.

Salt rejection phenomenon was investigated using armchair silicon carbide (SiC) nanotubes under applied electric fields. The systems included the (7,7) and (8,8) SiC nanotubes surrounded by silicon nitride membrane immersed in a 0.4mol/L aqueous solution of sodium chloride. Results of molecular dynamics (MD) simulations for selective separation of Na+ and Cl- ions showed that the (7,7) SiC nanotube is suitable for separation of cations and the (8,8) SiC nanotube can be used for separating anions. The water desalination by SiC nanotubes was demonstrated by potential of mean force for Na+ and Cl- ions in each SiC nanotube. Furthermore, the ionic current, ion residence time, and the radial distribution functions of species were measured to evaluate the properties of the system. Based on the results of this research, the studied SiC nanotubes can be recommended as a nanostructure model for water desalination.

Molecular dynamics simulations of trihalomethanes removal from water using boron nitride nanosheets.

Molecular dynamics simulations were performed to investigate the separation of trihalomethanes (THMs) from water using boron nitride nanosheets (BNNSs). The studied systems included THM molecules and a functionalized BNNS membrane immersed in an aqueous solution. An external pressure was applied to the z axis of the systems. Two functionalized BNNSs with large fluorinated-hydrogenated pore (F-H-pores) and small hydrogen-hydroxyl pore (H-OH-pores) were used. The pores of the BNNS membrane were obtained by passivating each nitrogen and boron atoms at the pore edges with fluorine and hydrogen atoms in the large pore or with hydroxyl and hydrogen atoms in the small pore. The results show that the BNNS with a small functionalized pore was impermeable to THM molecules, in contrast to the BNNS with a large functionalized pore. Using these membranes, water contaminants can be removed at lower cost.

Molecular dynamics simulation of non-covalent single-walled carbon nanotube functionalization with surfactant peptides.

Non-covalent functionalized single-walled carbon nanotubes (SWCNTs) with improved solubility and biocompatibility can successfully transfer drugs, DNA, RNA, and proteins into the target cells. Theoretical studies such as molecular docking and molecular dynamics simulations in fully atomistic scale were used to investigate the hydrophobic and aromatic π-π-stacking interaction of designing four novel surfactant peptides for non-covalent functionalization of SWCNTs. The results indicated that the designed peptides have binding affinity towards SWCNT with constant interactions during MD simulation times, and it can even be improved by increasing the number of tryptophan residues. The aromatic content of the peptides plays a significant role in their adsorption in SWCNT wall. The data suggest that π-π stacking interaction between the aromatic rings of tryptophan and π electrons of SWCNTs is more important than hydrophobic effects for dispersing carbon nanotubes; nevertheless SWCNTs are strongly hydrophobic in front of smooth surfaces. The usage of aromatic content of peptides for forming SWCNT/peptide complex was proved successfully, providing new insight into peptide design strategies for future nano-biomedical applications.

Removal of a hazardous heavy metal from aqueous solution using functionalized graphene and boron nitride nanosheets: Insights from simulations.

A computer simulation was performed to investigate the removal of Zn(2+) as a heavy metal from aqueous solution using the functionalized pore of a graphene nanosheet and boron nitride nanosheet (BNNS). The simulated systems were comprised of a graphene nanosheet or BNNS with a functionalized pore containing an aqueous ionic solution of zinc chloride. In order to remove heavy metal from an aqueous solution using the functionalized pore of a graphene nanosheet and BNNS, an external voltage was applied along the z-axis of the simulated box. For the selective removal of zinc ions, the pores of graphene and BNNS were functionalized by passivating each atom at the pore edge with appropriate atoms. For complete analysis systems, we calculated the potential of the mean force of ions, the radial distribution function of ion-water, the residence time of ions, the hydrogen bond, and the autocorrelation function of the hydrogen bond.

Removal of trihalomethanes from aqueous solution through armchair carbon nanotubes: a molecular dynamics study.

Molecular dynamics simulations were performed to investigate the removal of trihalomethanes (THMs) including CH3Cl, CH2Cl2 and CHCl3 from aqueous solutions by armchair carbon nanotubes (CNTs) under induced pressure. The studied system involved the armchair CNTs embedded between two graphene sheets with an aqueous solution of THMs in the simulation box. An external pressure was applied to the system along the z-axis of the simulation box. Six types of armchair CNTs with different diameter were used in this work, included (4,4), (5,5), (6,6), (7,7), (8,8) and (9,9) CNTs. The results of molecular dynamics simulation display that the armchair CNTs behave differently relative to THMs and water molecules. The permeation of THMs and water molecules through the armchair CNTs was dependent on the diameter of CNTs and the applied pressure.

Separation of a heavy metal from water through a membrane containing boron nitride nanotubes: molecular dynamics simulations.

Molecular dynamics simulations were performed to investigate the separation of zinc ions as a heavy metal from water using boron nitride nanotubes. The studied systems included boron nitride (BN) nanotubes embedded in a silicon-nitride membrane immersed in an aqueous solution of ZnCl2. An external electric field was applied to the system along the axis of the BN nanotubes. The results show that the (7,7) and (8,8) BN nanotubes were exclusively selective of ions. The (7,7) BN nanotube selectively conducted Zn(2+) ions, while the (8,8) BN nanotube selectively conducted Cl(-) ions. The results were confirmed using additional simulated parameters. The results indicate that the passage of ions through nanotubes is related to the diameter of the BN nanotubes.

Functionalized graphene as a nanostructured membrane for removal of copper and mercury from aqueous solution: a molecular dynamics simulation study.

The purpose of the present study was to investigate the removal of copper and mercury using functionalized graphene as a nanostructured membrane. The molecular dynamics simulation method was used to investigate the removal ability of these ions from aqueous solution using functionalized graphene membrane. The studied systems included a functionalized graphene membrane which was placed in the aqueous ionic solution of CuCl2 and HgCl2. An external electrical field was applied along the z axis of the system. The results indicated that the application of electrical field on the system caused the desired ions to pass through the functionalized graphene membrane. The Fluorinated pore (F-pore) terminated graphene selectively conducted Cu(2+) and Hg(2+) ions. The calculation of the potential of mean force of ions revealed that Cu(2+) and Hg(2+) ions face a relatively small energy barrier and could not pass through the F-pore graphene unless an external electrical field was applied upon them. In contrast, the energy barrier for the Cl(-) ion was large and it could not pass through the F-pore graphene. The findings of the study indicate that the permeation of ions across the graphene was a function of applied electrical fields. The findings of the present study are based on the detailed analysis and consideration of potential of mean force and radial distribution function curves.