Preparation of Nanomaterials Incorporated PMIA Loose Nanofiltration Membrane for Efficient Dye Wastewater Treatment

The development of efficient nanofiltration (NF) membranes is a critical challenge in the treatment of dye wastewater, particularly in achieving a balance between water permeability and selectivity. This work developed a nanomaterial-assisted mussel-inspired poly (m-phenylene isophthalamide) (PMIA) loose NF membrane with high permeability and excellent dye/salt selectivity. During fabrication, polyethyleneimine (PEI) was incorporated into the dopamine solution to promote uniform polymerization of dopamine, enhancing the homogeneity of the coating layer. Meanwhile, various titanium dioxide (TiO 2 ) nanoparticles were incorporated into the mussel-inspired solution to enhance membrane performance. The addition of TiO 2 increases the available free volume in the membrane's thin selective layer, thus enhancing the permeation of water molecules. The modified membrane demonstrated remarkable flux (153.77 L·m −2 ·h −1 ·bar −1 ), a Congo red (CR) rejection exceeding 98%, and a favorable CR/Na 2 SO 4 selectivity of 29.6. Notably, other nanoparticles, such as graphene oxide (GO), halloysite nanotubes (HNTs), silica (SiO 2 ), zeolitic imidazolate framework-L (ZIF-L), and polydopamine (PDA) modified silver (Ag), can also regulate the PDA-PEI coating structure, thereby synergistically enhancing the membrane's permeability. Moreover, the modified composite NF membrane can maintain excellent dye/salt separation performance under various operating conditions, indicating its great potential in dye desalination applications.