Enhanced CO2/N2 separation performance by using dopamine/polyethyleneimine-grafted TiO2 nanoparticles filled PEBA mixed-matrix membranes

Mixed matrix membranes (MMMs) were fabricated by incorporating synthesized titanium dioxide (TiO2) nanoparticles into polyether block amide (PEBA) matrix to fabricate TiO2/PBEA MMMs for CO2/N-2 separation. The mesoporous channels of TiO2 increased the density of active sites with high accessibility and also facilitate the diffusion of CO2 in the gas separation process. Furthermore, amine groups are grafted onto the TiO2 fillers via one step reaction with dopamine (DA) and polyethyleneimine (PEI). The modified TiO2 fillers with abundant amine groups are conductive to transfer CO2 owing to the reversible reaction occurred between CO2 and amine groups. The effects of TiO2 loading, DA/PEI modification on the morphology and CO2/N-2 separation performance of the resulting TiO2/PBEA MMMs were systematically studied. The results showed that the MMMs filled with 3 wt% DA-PEI-TiO2 synthesized with DA/PEI mass ratio of 1/1 and PEI molecular weight of 1800 exhibited optimal separation performance with CO2 permeability of 67 Barrer and CO2/N-2 selectivity of 101, surpassing the 2008 Robeson upper-bound.