A versatile superhydrophilic/air-superoleophobic glass fiber membrane: Fabrication and application in oil/water separation

Superwetting materials have received extensive interest owing to their potential for efficient oil/water separation. Herein, a superhydrophilic-superoleophobic glass fiber membrane was fabricated through a simple spraying coating method. The membrane was coated with a composite layer of methyltrimethoxysilane (MTMS), fluorosurfactant (FS-50) and TiO2 nanoparticles. Accordingly, both hydrophilic groups (i.e., -OH) and oleophobic groups (i.e., fluorinated groups) were distributed on the membrane, and its surface roughness was improved by TiO2. The contact angles of water and oil on the coated membrane were 0 degrees and 156.8 degrees in air, respectively. By virtue of its selective permeability, it demonstrated separation efficiencies larger than 99.2 % for oil/water mixtures, which remained 98.7 % after 40 separation cycles. Furthermore, its separation efficiencies for oil-inwater emulsions were over 98.3 %, which remained 98 % after 10 separation cycles. Owing to its strong superoleophobicity, it displayed prominent anti-oil-fouling performance both in air and underwater. Besides, presence of TiO2 endowed it with photocatalytic capability, enabling it to recover from organic dye pollution. Moreover, the coated membrane maintained superoleophobic after 10 sandpaper-abrading or squeezing cycles. It also exhibited excellent stability under acid/alkali/salt conditions. The study provided new insights for constructing superwetting materials and an effective strategy for oil/water separation.