▎ 摘　　要

In this study, a novel kind of facilitated transport membrane was prepared by incorporating zinc ion-modified graphene (GO-DA-Zn2+) nanosheets into a poly(ether-block-amide) (Pebax) matrix. Graphene oxide (GO) nanosheets were modified with zinc ion (Zn2+) by using dopamine-mediated complexation reaction. The CO2 separation properties of the facilitated transport membrane were evaluated using CO2/CH4 mixture as model system. The GO-DA-Zn2+ nanosheets played an important role in enhancing membrane performance. First, the high zinc ion loading (34.2 wt% of the nanosheets) could enhance the facilitated transport of CO2 based on pi-complexation mechanism, leading to a higher CO2 permeability and selectivity. Second, the incorporation of graphene nanosheets with high aspect ratio rendered more tortuous gas transport channels, which was favorable for hindering the penetration of CH4 with larger molecular size and thus enhancing the CO2/CH4 selectivity. Third, the fractional free volume of hybrid membrane was much elevated, also leading to higher CO2 permeability. The optimum separation properties of GO-DA-Zn2+ incorporated Pebax membranes were achieved with a CO2 permeability of 137.9 Barrer and a CO2/CH4 selectivity of 30.6, which were 49% and 78% higher than those of pristine Pebax membrane.