(614d) Confinement Effect on Water Transport in CNT Membranes : A Nonequilibrium Molecular Dynamics Study

Fluid transport through membrane has attracted broad attentions in recent decades due to their close association with wide industrial applications. Whereas massive experimental and simulation studies have been reported, the molecular mechanisms of fluid transport in nanopores are still urgent. Herein, we report a non-equilibrium molecular dynamics (NEMD) simulation study for elaborating the confinement effect of water transport through carbon nanotube (CNT) membranes. By varying the tube flexibility, inner surface wettability and pore size distribution (PSD), the permeability of water flow characterized with the flux enhancement rate is extensively examined. We find that the water enhancement rate in flexible tube is about 20% larger than that in rigid one. In addition, hydrophobic inner surface facilitates the water transport owing to the fast molecular slipping at the fluid-solid interface, and this facilitation becomes significant when the pore size is small. Finally, the pore size effect and pore size distribution are carefully taken into account when evaluating the total water flux through CNT membranes, and these treatments allow us to predict the water flux in a satisfactory agreement with reported experimental measurements. This work provides a quantitative simulation model toward the rational design of high efficient membrane.