Electrospun Fibrous Membranes with Dual-Scaled Porous Structure: Super Hydrophobicity, Super Lipophilicity, Excellent Water Adhesion, and Anti-Icing for Highly Efficient Oil Adsorption/Separation.

Developing highly efficient and multifunctional membranes toward oil adsorption and oil/water separation is of significance in oily wastewater treatment. Herein, a novel electrospun composite membrane with dual-scaled porous structure and nanoraised structure on each fiber was fabricated through electrospinning using biodegradable polylactide (PLA) and magnetic γ-Fe2O3 nanoparticles. The PLA/γ-Fe2O3 composite membranes show high porosity (>90%), superhydrophobic and superlipophilic performances with CH2I2 contact angle of 0°, good water adhesion ability like water droplets on a petal surface, excellent anti-icing performance, and good mechanical properties with a tensile strength of 1.31 MPa and a tensile modulus of 11.65 MPa. The superlipophilicity and dual-scaled porous structure endow the composite membranes with ultrahigh oil adsorption capacity up to 268.6 g/g toward motor oil. Furthermore, the composite membranes also show high oil permeation flux up to 2925 L/m2 h under the force of gravity. Even for oil/water emulsion, the composite membranes have high separation efficiency. We expect that the PLA/γ-Fe2O3 composite membranes can be used in oily wastewater treatment under various conditions through one-off adsorption or continuous oil/water separation, especially under low environmental temperature condition.