A durable biomimetic superhydrophilic/underwater superoleophobic fabric bed for highly efficient emulsion separation

A superhydrophilic/underwater superoleophobic fabric was fabricated via an immersion process in buffer solution of gallic acid (GA) and polyethyleneimine (PEI) and a short-term complexation process with cupric ions (Cu 2+ ). The fabric shows superhydrophilicity with a water contact angle (WCA) of 0° and underwater superoleophobicity with an underwater oil contact angle (UWOCA) of 162.2 ± 2.4°. Its superwettability can be kept after harsh acid/base/salty treatment, 1000 g sand impact and 50 cycles of tape-peeling, demonstrating outstanding chemical and physical durability. A fabric bed constructed by as-prepared fabrics was used for separating surfactant-stabilized toluene/isooctane/petroleum ether/1,2-dichloroethane-in-water emulsions, with separation efficiencies all over 99.1%. The separation efficiency could be retained above 99.1% after repeated separation, indicating excellent reusability of the fabric bed. • Underwater superoelophobic fabric was prepared by co-depositing GA/PEI particles and complexing with cupric ions. • The fabrication is facile and green with inexpensive raw materials. • The fabric shows excellent chemical and physical stability. • The fabric bed indicates high separation efficiency and reusability for emulsion separation.