Development of an antibacterial and visible photocatalytic nanocomposite microfiltration membrane incorporated by Ag₃PO₄/CuZnAl NLDH

Novel microfiltration mixed matrix membranes (MMMs) were successfully prepared by embedding the Ag₃PO₄/ZnAlCu nanolayerd double hydroxide (NLDH) nanocomposite into the polyethersulfone (PES) matrix. The results demonstrated that adding the Ag₃PO₄/ZnAlCu-NLDH nanocomposite improved the antifouling properties in the microfiltration process with the increase of hydrophilicity, porosity, surface pore diameter, and antibacterial properties. When the content of the nanocomposite was 0.5 wt%, the pure water flux was increased to 269.5 L m⁻² h⁻¹, as compared with the pristine PES membrane (229.2 L m⁻² h⁻¹). Surprisingly, it was found that embedding only 0.5 wt% of the Ag₃PO₄/ZnAlCu-NLDH nanocomposite in the PES matrix could spring up an antibiofouling membrane with the flux recovery ratio (FRR) of 62.3%, as compared to the pristine PES membrane with 50.9% of FRR. As confirmed by the inductively coupled plasma optical emission spectroscopy (ICP-OES), the copper and silver assembly in the PES membranes resulted in controlled leaching, proving that more than 95% of the added nanocomposite remained in the membrane after two months. The fabricated Ag₃PO₄/ZnAlCu-NLDH nanocomposite membranes also exhibited appreciable antibacterial efficiency against E. coli, Staphylococcus aureus, and B. anthracis. This study, therefore, suggests Ag₃PO₄/ZnAlCu-NLDH could be an effective additive to modify the PES microfiltration membrane for the development of MBR membranes.