Boosting CO2 transport in mixed matrix membranes by chitosan-MOF networks

The chitosan (CS)-grafted UiO-66-NH 2 (U6N) (CSGUN) was synthesized and incorporated into Pebax matrix to fabricate mixed matrix membranes (MMMs) for boosting CO 2 transport. The excellent CO 2 separation performance was exhibited for MMMs due to the following reasons: U6N with the suitable porosity and abundant CO 2 transport carriers can provide a unique “expressway” for CO 2 to boost CO 2 transport through MMMs. The grafting CS in CSGUN can connect Pebax (regular roads) and U6N (expressway), acting as an “on-ramp” between them to enrich CO 2 and guide CO 2 through U6N in an orderly manner. Thus, the constructed “on-ramp” and “expressway” in MMMs can improve CO 2 separation performance. Furthermore, the CS-MOF networks were formed in MMMs through using CS molecular chains to connect U6N for enhancing CO 2 separation performance of MMMs. Therefore, Pebax/CSGUN MMMs exhibited the excellent CO 2 separation performance with the CO 2 permeability of 558 ± 7 Barrer and the CO 2 /CH 4 selectivity of 37.5 ± 0.7. The study indicated that MMMs with CS-MOF bridged networks had great potential for boosting CO 2 transport by combining “expressways” and “on-ramp”.