Tailoring antifouling properties of hollow fiber membranes via controlled ZnO nanoparticle reinforcement for real water applications

Hollow fiber membranes are widely applied in water treatment due to their compact design and high surface area-to-volume ratio, yet their practical use is still hindered by fouling and structural instability. Here, we report a tailored approach to overcome these limitations by reinforcing polyethersulfone (PES) membranes with zinc oxide nanoparticles (nano-ZnO) synthesized under controlled precursor and calcination conditions. Among the tested routes, nano-ZnO derived from zinc acetate and calcined at 250 °C for 5 h exhibited exceptional colloidal stability and dispersion in N-methyl-2-pyrrolidone, enabling seamless integration into the membrane matrix. Incorporation of 4% nano-ZnO yielded hollow fiber membranes with a uniform asymmetric structure, improved hydrophilicity (60.6° contact angle), and enhanced antifouling behavior, reducing flux decline to 48.5% (vs. 65.9% for the control). These membranes achieved significant removal of real-water contaminants (28.1% COD, 93.2% turbidity, 69.2% color), demonstrating performance improvements under natural surface water conditions rather than model foulants. Higher nanoparticle loadings (6–8%) increased surface area but compromised structural integrity, underscoring the critical role of nanoparticle–polymer compatibility. This work highlights a reproducible pathway to engineer fouling-resistant membranes through controlled nanomaterial synthesis and incorporation, advancing the practical deployment of nanocomposite membranes for sustainable water treatment. • Membrane performance improved via in-house nano-ZnO synthesis; • Zinc acetate-based nano-ZnO ensured better performance in PES/NMP membranes; • High ZnO content (>4%) weakened the membrane structure via poor nanoparticle dispersion. • 4% nano-ZnO membranes showed 23.4% less flux loss than the control.