Robust Superhydrophobic/Superoleophilic Filter Paper with TiO2 Nanoparticles for Separating Oil-Water Mixtures and Surfactant- Stabilized Water-Oil Emulsions

Superwetting materials for oil-water separation have attracted increasing research attention recently. Developing cost-effective and high efficiency filter materials to separate oil-water mixtures and stable water-oil emulsions is challenging. Herein, the TiO2 nanoparticles were first hydrophobically modified using gamma-aminopropyltriethoxysilane, and then polydimethylsiloxane was subsequently added to obtain a stable superhydrophobic coating. The superhydrophobic filter paper was obtained via roll coating. The water contact angle on the coated filter paper exceeded 152 degrees, and the oil droplets were quickly absorbed by the coated filter paper. The superhydrophobic filter paper was used for separating various immiscible oil-water emulsions, with separation efficiencies of >99.5%. In addition, the synthesized filter paper can effectively separate various surfactant-stabilized water-oil emulsions. The separation efficiency was satisfactory even after 10 cycles. When the volume ratio of water in water-oil emulsions reached 20%, the separation efficiency exceeded 97.5%. The results indicate that the superhydrophobic/superoleophilic filter paper exhibits satisfactory oil-water separation ability and is environmentally friendly, cost effective, and easy to implement, making it suitable for continuous industrial production.