Enhanced CO2/N2 separation by porous reduced graphene oxide/Pebax mixed matrix membranes

Abstract

Computational simulations have suggested the enormous potential of using porous graphene-based materials for gas separation. However, this has yet to be demonstrated in a continuous and macroscopic membrane due to the difficulty in membrane fabrication. In this work, we reported a facile process to fabricate the partially porous reduced graphene oxide (PRG) nanosheets from graphene oxide (GO) via a wet chemical process. Then the fabricated PRG was blended into Pebax® 1657 polymer to prepare a mixed matrix gas separation membrane. In order to ensure good dispersion of the PRG nanosheets within the polymeric matrix, the reduction degree of GO should be carefully controlled. In addition, the residual functional groups on the partially reduced nanosheets surface facilitated the formation of highly efficient molecular sieving laminate structures within the mixed matrix membrane: the narrow gas flow galleries (average width of 0.34nm) between the neighbouring nanosheets ensured effective molecular sieving of CO2 against other larger gas molecules, while the mesoscopic pores on the laminate provided rapid gas transport pathways. Finally, the mixed matrix gas separation membrane had substantially improved CO2 permeability as well as CO2/N2 selectivity. This work is the first to report the fabrication of the porous GO-based gas separation membrane, and offers many opportunities to exploit the unique properties of porous GO in the fabrication of various molecular sieving membranes.