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• Mixed matrix membranes comprised of MXenes and nanocellulose were fabricated. • Incorporation of MXene nanosheets provided the membranes with gas transfer channels. • The hydrogen bonds boosted the interfacial affinity between MXenes and cellulose. • The intercalation of nanocellulose can enlarge the interlayer spacing of MXenes. • The optimal MMMs present CO 2 /N 2 and CO 2 /CH 4 ideal selectivities of 42.6 and 47.8. To achieve high capability mixed matrix membranes for CO 2 separation, it is vital to construct the suitable transport channels to enhance the diffusivity-enabled selectivity as well as an excellent affinity toward target gas molecules to increase the solubility-based selectivity. Herein, composite membranes were constructed by integrating two-dimensional MXene nanosheets into a carboxylated nanocellulose matrix. The carboxyl-rich cellulose interacts with the surface groups of MXene, which contributes to a superior interface compatibility and repairs the non-selective voids. In particular, one-dimensional nanocellulose can intercalate into MXene laminates to regulate the interlayer spacing and suppress the re-stacking of MXenes. The resulting MC-3 membrane (with a MXene loading of 15.4 wt%) possesses the optimal separation performance, bearing a CO 2 permeability of 156.7 Barrer with ideal selectivities of 47.8 for CO 2 /CH 4 and 42.6 for CO 2 /N 2. For the mixed gas separation, the MC-3 membrane exhibits separation factors of 48.5 and 55.3 for CO 2 /N 2 and CO 2 /CH 4 , respectively. This excellent separation performance is resulted from the enhanced interfacial property, suitable MXene channel size and good CO 2 -solubility of nanocellulose. [ABSTRACT FROM AUTHOR]

Membrane-based gas separation technology is becoming increasingly attractive as a feasible alternative for carbon capture to alleviate global warming. Here, a double-salt deep eutectic solvent (DES) composed of organic salt (choline chloride) and inorganic salt (ZnCl 2) is designed. The as-prepared DES exhibits a superb affinity and compatibility with nanocellulose because of the interactions between salt ions and cellulose carboxyl/hydroxyl groups. Through a solvent impregnation process, the DES was integrated into the nanocellulose gel precursor and used as a facilitated transport agent to form the functionalized nanocellulose membrane. The DES is tightly attached to the cellulose fibers with a high uniformity in the membrane matrix. Gas separation tests demonstrated that the DES@nanocellulose membranes presented a maximum CO 2 permeability of 155.8 Barrer, with CO 2 /N 2 and CO 2 /CH 4 ideal selectivities of 43.6 and 48.4, respectively. Mixed gas separation tests were performed and the optimal membrane exhibited separation factors of 48.1 and 52.3 for CO 2 /N 2 and CO 2 /CH 4 , respectively. The membranes provide a high solubility for CO 2 due to the presence of abundant zinc ions, choline cations and carboxyl groups in the network, which can establish reversible coordination with CO 2 and promote CO 2 transport. [ABSTRACT FROM AUTHOR]

Zeolitic imidazolate frameworks (ZIFs) hold great potential for carbon capture, while a major challenge for the practical application of ZIFs is the development of convenient three-dimensional bulk materials. Here, sustainable and biodegradable bacterial cellulose (BC) was used as the substrate for ZIF growth. Amino-functionalized ZIF-8 (ZIF-8-NH 2) was prepared within BC substrate via an in situ growth approach. ZIF crystals were wrapped uniformly over cellulose fibers and the chelating effect between metal (zinc) ions and hydroxyl groups makes the composites have high interface affinity and compatibility. The resulting foams presented a high CO 2 adsorption capacity of 1.63 mmol/g (25 °C, 1 bar). Moreover, ZIF-8-NH 2 @BC foams are facile to be regenerated by heating at 80 °C. This work provides a new avenue to construct ZIF/cellulose composites for gas treatment applications. • Amino-functionalized ZIF-8 was in situ prepared on bacterial cellulose substrate. • Good affinity and compatibility between BC and ZIF-8-NH 2 is observed. • ZIF-8-NH 2 @BC aerogel presents a high CO 2 adsorption capacity. • ZIF-8-NH 2 @BC aerogels exhibits better recyclability and portability. [ABSTRACT FROM AUTHOR]