Fabrication of sustainable and durable bio-polybenzoxazine based superhydrophobic cotton fabric for efficient oil/water separation

• The construction of superhydrophobic fabric is eco-friendly and versatile. • Superhydrophobic fabric demonstrated excellent chemical resistance and mechanical durability. • High separation performances of oil/water mixtures and water-in-oil emulsions were achieved. Sustainable and durable superhydrophobic cotton fabric was fabricated by combining the eco-friendly enzyme-etching approach and hydrophobic modification. The rough surface of the fiber was constructed by cellulase etching. Superhydrophobic cotton fabric was obtained from further deposition of cardanol-based polybenzoxazine (PC-aps) by dip-coating and thermal curing. The as-prepared PC-aps coated cotton fabric (PC-aps/ECF) possessed special wettability with a water contact angle (WCA) of 154.6° ± 0.4° and an oil contact angle of 0°. The PC-aps/ECF demonstrated exceptional mechanical durability and environmental stability to sandpaper abrasion, ultrasonic treatment, accelerated laundering, corrosive liquids, and high temperature. Moreover, the PC-aps/ECF had excellent separation performance for several oil/water mixtures with high oil flux (as high as 6744.6 ± 177.9 L m −2 h −1 ) and separation efficiency (all above 99.76 %). Especially, the separation of water-in-oil emulsions was achieved by external pressure filtration using the home-made PC-aps/ECF@PU sponge@ PC-aps/ECF composite with the oil flux up to 27473.2 ± 730.7 L m −2 h −1 bar −1 and the separation efficiency as high as 99.65 %. The outstanding durability, high separation performances, and excellent reusability of PC-aps/ECF make it very suitable for waste-water treatment.