Construction of the surface microstructure for PVDF/SMA@TiO2 hybrid membrane and the research of “cooperative repulsion-charge weakening” anti-oil fouling mechanism

In this work, the method of “vacuum filtration-physical adhesion” is used to uniformly load TiO 2 nanoparticles on the polymer membrane surface to form a continuous and uniform TiO 2 nanoparticle coating layer. Two distinct PVDF/SMA@TiO 2 hybrid membranes featuring diverse surface microstructures were prepared. The oil fouling resistance of the two membranes and their influence on oil droplet adsorption behavior were examined. The results indicated that introduction of TiO 2 nanoparticles imparts the membrane surface with a nano-rough structure while ensuring superhydrophilicity, features that inhibit oil droplet adhesion. The membrane achieved a flux recovery rate of 97.12 % and an oil removal efficiency of 98.9 %, demonstrating superior anti-fouling and separation capabilities. At the same time, the multiple synergistic mechanisms including a hydrophilic layer formed by continuous TiO 2 nanoparticles, low surface roughness, rigid structure of nanoparticles and electrostatic interaction effectively destroy the surface charge of the surfactant stabilized oil droplets, which results in the coalescence of small-size emulsion oil droplet into large-size oil droplet with less surfactant and relatively weak charge. Finally, the interfacial interaction at the oil droplet-membrane interface is attenuated. Based on these, the anti-fouling mechanism of “cooperative repulsion-charge weakening” was proposed. This research offers a theoretical foundation for designing high-performance hybrid membranes for oil-water separation.