Fabrication of MAF-6-based nanofiltration membranes and their application in dye/salt separation

The nanofiltration (NF) is a promising dye/salt separation technology for dye-containing wastewater reclamation. However, the membrane permeability and selectivity trade-off is still a critical issue for the conventional thin-film composite (TFC) membranes. This study investigates the fabrication and application of MAF-6-based NF membranes for efficient dye/salt separation. MAF-6 nanoparticles were synthesized using a rapid solution mixing method and incorporated into the polyamide (PA) layer of TFC membranes. The resulting thin-film nanocomposite (TFN) membranes were analyzed for their surface morphology, physicochemical properties, and separation performance. The introduction of MAF-6 nanoparticles significantly enhanced the permeability of the membranes while maintaining high selective rejection rates for dyes over salts. Specifically, membranes with 0.1 and 0.2 wt% MAF-6 loading exhibited superior permeability and separation efficiency. The enhanced performance was attributed to reduced cross-linking degree, improved hydrophilicity, and increased surface roughness of the PA layer. Long-term stability tests over 100 h demonstrated the robustness of the MAF-6 incorporated membranes. Additionally, the study elucidated the role of MAF-6 in the interfacial polymerization process, showing that it impedes monomer diffusion and influences the surface morphology of the PA layer. These findings highlight the potential of MAF-6 in tailoring membrane properties for advanced separation applications, particularly in the treatment of complex dye wastewater.