Advanced nanofiltration membrane fabricated on the porous organic cage tailored support for water purification application

The support layer have been recently recognized as an important factor in tailoring the performance of thin film composite membranes, but until now limited methods are available to optimize the support properties for the fabrication of high-performance nanofiltration (NF) membrane. Herein, Noria, one kind of porous organic cages, was employed as the filler to prepare Noria hybrid polysulfone (PSF) support through non-solvent-induced phase separation (NIPS). Owing to its good solubility in N-methylpyrrolidone, the blended Noria could distribute in the dope solution homogeneously and the structure and surface properties of the resulting support were finely tuned. Assisted from the inner cavity of Noria as well as enhanced hydrophilicity, the pure water flux of support membrane with a Noria loading of 3.60 wt% reached 125 L m−2 h−1 bar−1, which was nearly 2.5-fold higher than the pristine one. In addition to that entrapped in the PSF chains, a mass of Noria molecules aggregated on support surface during the NIPS process and they could be further etched by alkaline solution, in situ enlarging the surface pore size. After the interfacial polymerization (IP), the NF membrane fabricated on the etched support depicted excellent performance compared with those incorporated with other fillers either in the support or in the polyamide layer. Furthermore, this study could promote the understanding about the role of support in the IP process for the preparation of TFC membranes.