Nanoscale Fluid Mechanics Working Principles of Transverse Flow Carbon Nanotube Membrane for Enhanced Desalination

Abstract

This work introduces the transverse flow carbon nanotube (CNT) membrane, a novel membrane configuration designed to separate salt from water efficiently. The transverse flow CNT membrane uses transverse flow across horizontally stacked CNT, with neighboring CNT separated by a critical slit size. Through molecular dynamics (MD) simulation, the nano-fluidics interactions involved in the separation of salt from water using the transverse flow CNT membrane is studied. The simulation shows that this new membrane offers superior desalination performance, with permeability more than two times that of atom-thick graphene slit membrane, and orders of magnitude higher than conventional membranes. The effects of the nano-channels formed by the transverse flow CNT membrane on the behavior of water molecules and salt ions in a desalination system are studied in further detail with thermodynamic free energy computations, oxygen density mapping and hydrogen bond network studies. This simple but effective design offers an alternative solution for the practical use of CNT for efficient desalination.