Robust superhydrophobic ceramic particles with pH-induced wettability conversion for highly efficient oil-water separation

While stimulus-responsive separation materials hold great promise for oil-water separation, their development is often constrained by complex fabrication processes, reliance on fluorinated chemicals, or harsh synthesis conditions. This study proposed a simple, fluorine-free dip-coating strategy that required no external strong acids, successfully fabricating decanoic acid-modified copper/titanium ceramic particles (CP-DCT) with pH-responsive switching between superhydrophobicity and superhydrophilicity. The key to this approach lay in the utilization of a Ti-O-Ti self-assembled layered network to efficiently anchor decanoic acid under mild conditions, achieving synergy between stable superhydrophobicity (water contact angle of 163.2 ± 4.2°) and dynamic wettability regulation. The material not only delivered a separation efficiency of 99.7% and a permeation flux of 3.06 kL·m⁻²·h⁻¹ for dichloromethane water-in-oil emulsions, but also exhibited remarkable operational robustness-maintaining stable performance after ten separation cycles, exposure to 200 °C high temperature, ultrasonication, or chemical corrosion. Theoretical analysis revealed that its high performance originated from capillary effects induced by the surface micro/nano-structure combined with controllable wettability, consistent with predictions from Young-Laplace theory. This work broke through the limitations of conventional stimulus-responsive materials in terms of preparation sustainability and applicability, offering a new material prototype and design strategy for developing intelligent separation media suited for real-world complex environments.