Chapter 15 - Novel Graphene Membranes – Theory and Application

Abstract

Two-dimensional (2D) materials offer unique characteristics for membrane applications for water treatment. With its monatomic thickness and controllability of stacking, graphene, in particular, has drawn great interest in the research and development area of novel membrane materials. This chapter provides an overview of the research conducted in this area. Unique properties of graphene are introduced such as the unique diffusion barrier properties of pristine single crystalline graphene. Recent research work has shown that, if well perforated, the thinnest feasible membrane can be created to allow ultimate permeation at given pore sizes that agrees with predictions of the 2D orifice flow theories for continuum pore sizes. For subcontinuum pores, molecular dynamics simulations predict potential salt rejection with potential desalination applications. Another novel membrane architecture is the stacking of individual layers of 2D materials. When graphene-based platelets are chemically modified and stacked, the space between individual platelets forms a narrow transport pathway of controlled sizes that reveals the possibility of size exclusion of gases and solvated ions. Both approaches of membrane formation – porous ultrathin graphene as well as stacked platelets – offer remarkable flux and selectivity and, therefore, represent a very promising prospect for new membranes for water technology applications.