Mixed matrix membranes (MMMs) made from inorganic fillers and polymers is a kind of promising candidate for gas separation. In this work, two‐dimensional MXene nanosheets were synthesized and incorporated into a polyether‐polyamide block copolymer (Pebax) matrix to fabricate MMM for CO2 capture. The physicochemical properties of MXene nanosheets and MXene/Pebax membranes were studied systematically. The introduction of MXene nanosheets provided additional molecular transport channels and meanwhile enhanced the CO2 adsorption capacity, thereby enhancing both the CO2 peremance and CO2/N2 selectivity of Pebax membrane. The optimized MXene/Pebax membrane with a MXene loading of 0.15 wt % displayed a high separation performance with a CO2 permeance of 21.6 GPU and a CO2/N2 selectivity of 72.5, showing potential application in CO2 capture.
We highlighted the similarities/differences between zeolites and MOFs in adsorption and membrane separation and discussed the feasibility of adsorbent-to-membrane separation.
Mixed‐matrix membranes (MMMs), judiciously combining processability of polymer and remarkable separation performance of nanofillers, have been extensive pursuits for molecular separation process. Permeability matching between filler and polymer is one of the necessary requisites to desirable mixed‐matrix effect. Considering the superior molecular sieving effect of UTSA‐280 metal‐organic frameworks on C2H4 and C2H6, here, we report two types of UTSA‐280/6FDA‐polyimide MMMs toward C2H4/C2H6 separation. The molecular sieving effect of UTSA‐280 endowed 6FDA‐DAM:DABA(3:2) membrane with simultaneous improvements in C2H4 permeability and C2H4/C2H6 selectivity. Optimally, when the filler reached 21.80 wt%, C2H4 permeability and C2H4/C2H6 selectivity was increased to 6.49 Barrer (by 15%) and 4.94 (by 32%), respectively. On the contrary, UTSA‐280/6FDA‐DAM MMMs showed undesirable mixed‐matrix effect that C2H4 permeability decreased meanwhile C2H4/C2H6 selectivity nearly kept at polymeric pristine membrane level. It was found that permeability matching between two phases was responsible to these opposite mixed‐matrix effects. More specifically, UTSA‐280 had a relatively low gas permeability so that it required a less permeable polymeric matrix like 6FDA‐DAM:DABA(3:2) to exert its molecular sieving effect. Furthermore, the optimal‐matching 6FDA‐matrix in permeability with UTSA‐280 fillers was predicted by theoretical model. This work not only reports improving C2H4/C2H6 separation performance via mixed‐matrix formulation, but also emphasizes the importance of permeability matching between polymer and filler to realize the mixed‐matrix effect.
Aromatics-permeable membranes ……made from polydimethylsiloxane with tunable side group mobilities are reported by Gongping Liu and co-workers in their Research Article (e202111810). Phenyl groups were introduced as rigid molecular spacers to endow the methyl groups with high mobility and reconstruct the polymer conformation, creating ah ighway for the fast transport of aromatic molecules,a nd thus realizing efficient removal of aromatic compounds from aqueous solution.
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