Fully organic and biodegradable superhydrophobic sponges derived from natural resources for efficient removal of oil from water

• A fully organic and biodegradable superhydrophobic sponge is rationally constructed. • All of raw materials are derived from cheap renewable natural resources. • The sponge presents great separation performance for immiscible oil/water mixtures. • Multi-layer compressed porous structure achieves gravity-driven high-flux emulsion separation. Facile fabrication of functional superhydrophobic porous materials with full biodegradability for efficient removal of oily pollutants from water has been of considerable interest for its great significance in environmental protection. Herein, a fully organic and biodegradable superhydrophobic sponge is fabricated with carnauba wax (CW) via dip-coating, nonsolvent induced phase separation and spraying processes on a freeze-dried pomelo peel. The as-fabricated sponge was covered with flower-shaped patterns aggregated by CW nanosheets, and presented great water repellency with a contact angle of 154°. Thanks to the 3D porous architecture and superhydrophobicity/superoleophilicity, the sponge exhibited great oil absorptive capacity, oil selectivity, separation efficiency and reusability for immiscible oil/water mixtures. Interestingly, the multi-layer compressed sponges realized gravity-driven surfactant-stabilized water-in-oil emulsion separation with high permeation flux of up to 5729 L·m −2 ·h −1 and excellent efficiency of oil purity larger than 99.9%. Importantly, the superhydrophobic sponge was derived from cheap renewable natural resources, and capable of being completely biodegraded after discarding. The findings conceivably stand out as a new tool to fabricate superhydrophobic materials with sustainability and biodegradability for oil accidents and industrial sewage emissions.