Two-step surface functionalization/alignment strategy to improve CO2/N2 separation from mixed matrix membranes based on PEBAX and graphene oxide

TLDR: In this article , a simple method to prepare mixed matrix membranes (MMM) based on Pebax with functionalized/oriented graphene oxide (GO) nanosheets is presented to improve CO 2 /N 2 separation.

Abstract: In this study, a simple method to prepare mixed matrix membranes (MMM) based on Pebax with functionalized/oriented graphene oxide (GO) nanosheets is presented to improve CO 2 /N 2 separation. First, the GO nanosheets were surface modified with different amounts of m-phenylenediamine (mPD) to maximize the CO 2 adsorption affinity and minimize GO agglomeration within the matrix. Then, an external electric field was applied to organize/orient the GO nanosheets (modified and unmodified) during membrane preparation. The separation performance results showed that the CO 2 permeability of unmodified and amine-functionalized GO-filled MMM respectively increased by 1.7 and 2.1 times compared to the neat matrix. This improvement is attributed to the high affinity of amino groups for CO 2 uptake. Furthermore, applying a vertical electric field increased the CO 2 permeability compared to a random GO orientation state by 1.3 and 2.8 times for the unmodified and modified GO-filled MMM, respectively. This significant improvement is related to a lower tortuosity in the membrane, improving the passage of gas molecules. Overall, the combination of surface treatment (amino group) and orientation (electric field) on GO nanosheets leads to better CO 2 permselectivity for the membranes studied.