Fabrication and Characterization of Polysulfone-Graphene Oxide Mixed Matrix Membranes for Reduction Permeability and Selectivity of CO2, N2, CH4 Gases

Abstract

Reduced graphene oxide is fabricated from graphite oxidation through a modified Hummer method. The polysulfone fabricated by a phase separation method. Different amounts of graphene oxide (0.0, 0.25 and 0.5 wt.% of polymer) were used. After preparation of the membranes, the cross-sectional structure and their upper surface were assessed by scanning electron microscopy (SEM) and the surface roughness of the membranes was assessed by atomic force microscopy (AFM). From SEM, an increase in the concentration of graphene oxide in the polymer matrix resulted in a thicker sponge layer and disappearance of the finger-like cavities. From the gas permeation test, by addition of 0.25% graphene oxide to the polymer matrix, CO₂ permeability was increased from 62 GPU to 77 GPU, while addition of 0.5 wt.% resulted in a lower permeability (69.55 GPU). Nitrogen gas permeation flux of membranes decreased from 10.93 GPU to 4 GPU by addition of 0.50 wt.% of graphene oxide. Methane gas permeation flux is reduced from 11.5 GPU to 7 GPU and 4.92 GPU by addition of 0.25% and 0.50% graphene oxide, respectively. and CO2/N2 selectivity for all three membrane samples: 5.8, 12.3 and 17.9 respectively. And CO2/CH4 selectivity was obtained: 5.43, 10.95 and 14.2.