Fabrication of cellulose nanofibrils/UiO-66-NH2 composite membrane for CO2/N2 separation

Incorporating metal-organic frameworks into cellulose matrix to prepare composite membranes is promising in gas-separation applications. In this study, UiO-66-NH2 (Zr-based MOF) nanoparticles are wrapped into the densely packed cellulose nanofibrils (CNF-COOH) via a facile vacuum filtration process. The existence of acid-base interactions and electrostatic forces between UiO-66-NH2 and CNF-COOH renders ideal interfacial morphology. Results show that UiO-66-NH2 is cross-linked by -COOH groups and well-dispersed in the CNF matrix. The porous UiO-66-NH2 strengthens the diffusion process of CO2 molecules, thus elevating the permeation flux and separation factor simultaneously. The optimum separation performance is achieved over CM-1 membrane with a CO2 permeability of 139 Barrer and a CO2/N2 selectivity ratio of 46.