(226b) Graphene Oxide Membranes for Gas Separation – Gas Transport Mechanism

Graphene oxide (GO) membranes have shown promising gas separation characteristics specially for hydrogen that make them of interest for industrial applications. However, the gas transport mechanism for these membranes is unclear due to inconsistent permeation and separation results reported in literature. It appears that synthesis method and characteristics of GO sheets (size or defects) affect the permeability and separation characteristics of these membranes. This talk will give an overview of our recent progresses on GO membranes for gas separation with a focus on clarifying the transport mechanism of these membranes. An inter-sheet and intra-sheet two-pathway model is proposed to explain the permeation and separation results of GO membranes obtained in our study. We found that gas permeation and separation through GO membranes is controlled by transport through inter-sheet space of extremely high tortuosity and intra-sheet defects of extremely low porosity. The GO membrane structure that defines both transport pathways is difficult to control leading to variation of permeation and separation properties reported in the literature. We also investigated structure changes and gas permeation properties of GO membranes made by different synthesis methods, sheet sizes, and GO sheet prepared by different oxidation methods (Hummers vs Brodie). We also, demonstrated a scalable fabrication of GO membranes on polyester track etch polymer substrates by easily scalable spray coating technique. Our recent study on membrane fabrication with narrow interlayer spacing height show improved (H₂/CO₂) separation performance.