A bio-inspired green method to fabricate pH-responsive sponge with switchable surface wettability for multitasking and effective oil-water separation

•A simple and environment-friendly method was proposed to prepare pH-responsive sponge.•The repeated wettability transition between superhydrophobicity and superhydrophilicity was achieved.•Driven by a pump, the sponge can achieve two opposite modes of continuous oil-water separation.•The sponge with switchable wettability can efficiently separate various oil-water mixtures by absorption or filtration.