title: Nonequilibrium molecular dynamics simulation of pressure-driven water transport through modified CNT membranes.
abstract: Nonequilibrium molecular dynamics (NEMD) simulations are presented to investigate the effect of water-membrane interactions on the transport properties of pressure-driven water flow passing through carbon nanotube (CNT) membranes. The CNT membrane is modified with different physical properties to alter the van der Waals interactions or the electrostatic interactions between water molecules and the CNT membranes. The unmodified and modified CNT membranes are models of simplified nanofiltration (NF) membranes at operating conditions consistent with real NF systems. All NEMD simulations are run with constant pressure difference (8.0 MPa) temperature (300 K), constant pore size (0.643 nm radius for CNT (12, 12)), and membrane thickness (6.0 nm). The water flow rate, density, and velocity (in flow direction) distributions are obtained by analyzing the NEMD simulation results to compare transport through the modified and unmodified CNT membranes. The pressure-driven water flow through CNT membranes is from 11 to 21 times faster than predicted by the Navier-Stokes equations. For water passing through the modified membrane with stronger van der Waals or electrostatic interactions, the fast flow is reduced giving lower flow rates and velocities. These investigations show the effect of water-CNT membrane interactions on water transport under NF operating conditions. This work can help provide and improve the understanding of how these membrane characteristics affect membrane performance for real NF processes.
authors.affiliation: Department of Chemical Engineering, McMaster University, Hamilton, Ontario L8S 4L7, Canada.
authors.forename: Luying
authors.initials: L
authors.lastname: Wang
authors.forename: Randall S
authors.initials: RS
authors.lastname: Dumont
authors.forename: James M
authors.initials: JM
authors.lastname: Dickson
mesh_terms: D056004:Molecular Dynamics Simulation; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010316:Particle Size; D011312:Pressure; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; D014867:Water