The metal organic framework of UiO-66-NH2 reinforced nanofiltration membrane for highly efficient ion sieving

Metal organic framework (MOF) with fine pore structures, ultra-high porosity and large specific surface area can provide more water transport channels while achieving precise sieving of different sizes of ions, which is a promising material for high efficiency desalination. However, particle agglomeration, interface incompatibilities and interface defects severely restrict the performance of MOF-based membranes. It is still a challenge to construct MOF-based desalination membranes with both high water permeability and high ion sieving. Herein, the UiO-66-NH2 based nanofiltration membrane was fabricated by in-situ growth of UiO-66-NH2 on Nylon membrane and composed with polyamide (PA) layer by interfacial polymerization (IP). With 12 h solvothermal reaction, the UiO-66-NH2 nanoparticles are found uniformly loaded on the Nylon substrate. Therefore, the water molecule transport channels provided by UiO-66-NH2 nanoparticles reduce the transport resistance, which can improve the water permeability. More importantly, UiO-66-NH2 nanoparticles are found to be involved in the IP process, which can reduce the interfacial defects and thus enhance the bonding force between the PA layer and base film. The synergistic effect of the UiO-66-NH2 and PA layer improves the nanofiltration performance of the membrane with rejection rate of 92.97% for Na2SO4 and the pure water permeance (PWP) of 11.55 L m- 2 h-1 bar-1. The N-UN12 @PA membrane also has excellent antifouling performance (flux recovery ratio (FRR) of 95.86%, reversible fouling ratio (Rr) of 33.93%, irreversible fouling ratio (Rir) of 4.14%). Unlike the mixed -matrix membrane (MMM) and polycrystalline MOF membrane, this strategy provides a promising method to prepare high-performance nanofiltration membrane for desalination.