Developing UV-light driven photocatalytic PSf/Ni-doped ZnO/PDA membrane with superior antifouling, self-cleaning, and self-protecting performances for handmade batik wastewater treatment

Ultrafiltration UV light-driven photocatalyst composite membranes, with distinctive antifouling, self-cleaning, and self-protection capacities, were simply synthesized using a Ni-doped ZnO photocatalyst to enhance the functional properties of polysulfone (PSf) membranes. The manufacturing process involved soaking of PSf membrane sheet in a dopamine solution to allow self-polymerization of polydopamine (PDA) on the membrane surface. PDA coating led to increase membrane surface roughness and incorporation of numerous hydroxyl and amine groups, which play role in the reduction of interactions with impurities. The results of FTIR, XRD, mechanical properties, and surface physicochemical properties confirmed that the optimum duration for PDA polymerization to achieve the preferred membrane performance was 2-h. This was supported by high membrane's stability in terms of productivity and photocatalytic activity for the processing of handmade batik wastewater (BWW). Furthermore, the membranes also possess an improved antifouling property, with a flux recovery ratio (FRR) of nearly 100%. The membrane also exhibited preserved self-cleaning and self-protection abilities after being operated for five consecutive cycles under UV light irradiation, with flux recovery and pollutant rejection rates exceeding 90%. These findings suggest that the 2-h PDA-coated composite membrane is the most suitable membrane for efficient processing of highly polluted wastewater, particularly handmade batik and other textiles wastewater.