Newly developed nanofiltration (NF) composite membranes by interfacial polymerization for Safranin O and Aniline blue removal

In this study, new thin-film-composite (TFC) nanofiltration (NF) membranes were developed through interfacial polymerization (IP) on the lumen side of hollow fiber support membranes by exploring novel combinations of reacting monomers and optimizing the fabrication conditions. By varying the different combinations of reacting monomers, the molecular weight cut off (MWCO) of NF membranes in a hollow fiber module can be adjusted to approximately 300.0 g mol−1 with a high pure water permeability of 3.1 L m−2 h−1 bar−1 at 3.0 bar. These hollow fiber NF membranes demonstrated different rejections for different salts in the order of R(Na2SO4)>R(MgSO4)>R(NaCl)>R(MgCl2) and high pressure resistance. These membranes were further tested for the removal of typical dyes in aqueous solutions under varying conditions. For both the Safranin O and the Aniline blue dyes, the rejection was higher than 90% under the tested conditions, and the excellent performance of the NF membranes in the removal of dyes from wastewater was maintained over a wide pH range; the best performance was obtained at a pH of 11. Therefore, the novel NF membranes are promising for the removal of crucial dyes as a next-generation technology for industrial wastewater treatment.