Search

• 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]

Mixed matrix membranes (MMMs) combine the advantages of both polymers and inorganic fillers, and hold great promise for industrial gas separation. In this work, to enhance the interfacial compatibility between cellulose acetate (CA) matrix and ZIF-8 crystals, an interfacial design strategy was proposed by grafting polyethylenimine (PEI) onto ZIF-8 particles. The introduction of amine-rich PEI could regulate the surface property and maintain the pore accessibility of ZIF-8 crystals. In addition, the amine groups in PEI could interact with hydroxyl/carbonyl groups in CA chains to suppress the non-ideal voids at the ZIF-8/CA interface. With the aid of PEI, the interfacial compatibility between ZIF-8 and CA is substantially enhanced. Compared with pristine CA and ZIF-8@CA membranes, PEI grafted ZIF-8@CA (PZIF-8@CA) membrane exhibits a better gas separation performance, bearing a CO 2 permeability of 150.3 Barrer with CO 2 /N 2 and CO 2 /CH 4 ideal selectivities of 44.2 and 53.7, respectively. The separation mechanisms are attributed to the superior interfacial property, the good dispersion of ZIF-8 particles, the amine groups in PEI, and the high CO 2 solubility of the CA matrix. [Display omitted] • PEI grafted ZIF-8 (PZIF-8) is introduced into cellulose acetate to obtain MMMs. • PEI boosts the interfacial compatibility between ZIF-8 and cellulose acetate. • The optimal PZIF-8/CA membrane has a CO 2 permeability of 150.3 Barrer. • The membrane has CO 2 /N 2 and CO 2 /CH 4 ideal selectivities of 44.2 and 53.7 [ABSTRACT FROM AUTHOR]