Fabrication of a novel composite nanofiltration membrane with effective treating dye wastewater via integration of phase inversion and interfacial polymerization

In this work, we proposed using the combination of nonsolvent induced phase separation (NIPS) technology and interfacial polymerization (IP) process upon polyvinylidene fluoride (PVDF) substrate as a novel and simple method for preparing high-flux composite nanofiltration membranes. The surface chemical properties, physical structure, hydrophilicity, zeta potential, and permeation experiments of the composite membranes that were prepared with graphene oxide (GO), cyclodextrin (CD), or GO@CD as aqueous monomers were studied. The results indicated that the selective polyester active layer successfully covered the PVDF substrate, and the optimal GO@CD50/PVDF membrane was fabricated using the modification conditions of 1.0 wt% of GO@CD50, 5 min of phase transition time, 0.2 wt% of TMC, and 60 min of IP reaction time, which achieved a high pure water flux (84.8 L m−2 h−1 bar−1) and dye permeation flux (48.7 L m−2 h−1 bar−1 for Rose Bengal); in addition, the dye rejection rate was also high (e.g., 99.6 % for Rose Bengal). Besides, CD nanomaterials can be effectively inserted into the GO lamella to increase the layer spacing of GO sheets and expose more oxygen-containing functional groups; this, in turn, enhances the long-term stability and permeability of the membrane. This study provides practical ways to treat dyes wastewater.