Polydopamine Mediated Fractal Silica Nanoparticles Deposition on PES Membrane for Enhanced Oil–Water Separation

ABSTRACT A hydrophilic polyethersulfone (PES)–polydopamine (PDA)–fractal silica nanoparticle (FSN) membrane was fabricated via vapor‐induced phase separation followed by polydopamine‐mediated anchoring of fractal silica nanoparticles. The hierarchical micro−/nano‐rough surface endowed the PES‐PDA‐FSN membrane with a water contact angle of 26.5° ± 1.1° and a 52% higher pure‐water flux (8210 L m −2 h −1 bar −1 ) compared to the pristine PES membrane (5429 L m −2 h −1 bar −1 ). The oil‐in‐water emulsion flux increased from 560 L m −2 h −1 bar −1 (pristine PES) to 2640 L m −2 h −1 bar −1 after modification. The modified membrane also exhibits excellent anti‐fouling performance. The total oil fouling ratio decreased from 89.69% (PES) to 67.72% (PES‐PDA‐FSN). The irreversible fouling ratio showed a more pronounced reduction from 44.56% (PES) to 8.53% (PES‐PDA‐FSN). Even after three emulsion filtration cycles, the irreversible fouling ratio of the PES‐PDA‐FSN membrane (56.15%) remained lower than that of the PES membrane (79.55%). This superior performance is attributed to the micro/nano surface structure formed by the synergistic effect of the hydrophilic PDA layer and the uniform, stable distribution of FSN on the surface. The scalable strategy not only provides an effective, facile method for constructing composite membranes but also offers a practical route for industrial oily wastewater treatment.