GRAPHENE-BASED MEMBRANES: RATIONAL DESIGN AND NANOFLUIDICS

Abstract

Nanostructured graphene-based membranes combine high water flux with selective ionic and molecular permeability. The size and charge of the functionalites of graphene-oxide (GO) define the percolative path of graphenic channels available for the net transport across the membrane. Herein, we embarked on a rational-design of functionalised GO membranes to disentangle contribution of hydration, chemical and electrostatic interactions to the ionic and water transport. We controlled the oxidation process in GO to tune the interplanar spacing of the lamellar structure, affecting ionic dehydration. Furthermore, by covalent grafting of positively-charged groups onto GO we developed dipolar membrane that bears resemblance to zwitterionic molecules, making it highly hydrophilic with controllable ionic selectivity and electrokinetic stability. Finally, we show that by incorporating silk fibroin into the GO membrane, improved both water fluxes and salt rejection. The scalability of these membranes make them strong candidates for applications including biochemical separation, desalination, and osmotic power generation.