High Rejection Performance Ultrafiltration Membrane with Ultrathin Dense Layer Fabricated by Movement and Dissolving of Metal-organic Frameworks

Ultrafiltration membrane has potential to solve the problem of water pollution and shortage of water resources. In order to obtain good solute selectivity, people often introducing a new dense layer on the surface of membrane, which fails to achieve the purpose of obtaining the maximum permeability and solute selectivity with the minimum transport resistance. In this study, a metal-organic framework (ZIF-67) is prepared band blended with polyether sulfone as a modification additive to construct an ultra-thin dense layer structure for the ZIF-67 modified PES membrane (M-PES/ZIF-67). The thickness of M-PES/ZIF-67 dense layer decreases with the increase of ZIF-67 content, and the thickness is reduced to 123 nm. Therefore, the resistance of water transport on the dense layer is reduced, thereby the permeability of PES membrane increased. When ZIF-67 content is 4 wt.%, the water flux of M-PES/ZIF-67 is 55.696 L m-2 h-1, and the high rejection ratio of bovine serum albumin and congo red are 98 and 97 %, respectively. Thus, via adjusting the thickness of dense layer can improve the permeability of M-PES/ZIF-67 and retain the solute selectivity of the membrane, which has the potential to be used as water treatment membrane.