The influence of intermediate layer and graphene oxide modification on the CO2 capture efficiency of Pebax-GO/PDMS/PSf mixed matrix composite membranes

Background: Greenhouse gasses are still a global concern where minimization of or controlling its emission should be prioritized. This could be efficiently resolved through membrane separation technology. Methods: Herein, a mixed matrix composite membrane made from poly(dimethylsiloxane) (PDMS), Pebax® MH1657 (Pebax), and 3-(Aminopropyl)triethoxysilane (APTES)-modified graphene oxide on a polysulfone (PSf) substrate was prepared. The hydrophilicity of PDMS intermediate layer was improved by UV/O3 treatment. While the concentrations of Pebax and APTES-GO loading were varied to observe the combined effects of active and intermediate layers on CO2 capture. Significant findings: The membrane with 1 wt% GO loading had the optimal gas separation performance with a CO2 permeability of 54.5 GPU and a CO2/N2 selectivity of 36.9 at 35 °C and 0.1 MPa. The separation was further improved with APTES-functionalized GO (aGO). The mixed matrix composite membrane with 1 wt% aGO loading augmented the CO2 permeance to 208.9 GPU with a CO2/N2 selectivity of 40 at 35 °C and 0.7 MPa. The amine groups augmented the CO2 adsorption and selectivity and provided enhanced membrane stability that can also be operated at higher pressure. This study provides an understanding on the function of each layer on a gas separation mixed matrix composite membrane.