Highly Efficient Production of Mullite Sponges with Ultralight and Superelastic via Solution Blow Spinning for Oil–Water Separation

Oil leakage has become a global public environmental problem and has caused serious harm to the global environment. Inorganic nanofibers with high porosity, large specific surface area, and excellent high temperature resistance have a wide application prospect in oil–water separation. In this study, we prepared mullite nanofiber (MNF) sponges for efficient oil–water separation using electrostatic-assisted solution blow spinning (E-SBS) and characterized its morphology, structure, mechanics, thermal stability, and oil–water separation. The results show that MNF sponge has ultralight weight (5.135 mg cm^–3) and excellent temperature resistance (−196 to 1300 °C). Further, the sponge maintained 73% of its initial stress after 100 compression cycles; it did not deform significantly after high-temperature or liquid nitrogen treatment, showing excellent mechanical properties. Most importantly, after WD-10 modification, MNF sponges maintained high oil throughput ((oil-in-water oil flux >1600 L m^–2 h^–1), (oil–water mixture oil flux >7000 L m^–2 h^–1)), separation efficiency (>98%), and contact angle (>139°) after 20 separation experiments. More importantly, the preparation process of electrostatic assisted solution spray spinning MNF sponge is environmentally friendly and pollution-free and can be mass produced. Therefore, MNF sponges will have a very large application potential in the field of oil–water separation.