Self-indicating and recyclable superhydrophobic membranes for effective oil/water separation in harsh conditions

A durable and renewable superhydrophobic and superoleophilic poly(m-phenyleneisophthalamide)/silicon dioxide (PMIA/SiO2) membrane was prepared for oil/water separation in harsh conditions, the membrane have a self-indicating capacity when it is to become inoperable. Its nanoroot-shaped micro-nanostructure was achieved by covering each individual electrospun PMIA/SiO2 nanofiber with a dense silicone nanofilament layer to form a superhydrophobic surface, the water contact angle was more than 150°and the sliding angle was less than 1°. The porous nanofiber network served as a substrate to ensure the high absorption capacity of oils and oil/water separation efficiency, and increase the roughness for hydrophobicity . Its superhydrophobicity, high separation efficiency, and excellent stability and durability in oil/water separations under various extreme conditions, such as high temperature, acid/alkali solutions, and seawater for long periods can be preserved. This behavior is attributed to the robust micro-nanostructure, superior corrosion resistance , and excellent mechanical properties . Congo red in the PMIA substrate acts as a color indicator to indicate superhydrophobic surface failure, and the disabled material can be recovered absolutely by in-situ regrowth of silicone nanofilaments. This material is expected to become a highly effective renewable and sustainable material for oil-spill cleanup and recycle.