Bioinspired Anti-Oil-Fouling Hierarchical Structured Membranes Decorated with Urchin-Like α-FeOOH Particles for Efficient Oil/Water Mixture and Crude Oil-in-Water Emulsion Separation

Designing and constructing a stable water-retention layer acting as the isolation between the oil and membrane surface holds great significance for solving the membrane fouling problems in oil/water separation, including common layered oil/water mixtures, immiscible oil-in-water emulsions, and even high-viscosity crude oil-in-water emulsions. Inspired by the self-cleaning property of sea urchin thorns, a bioinspired anti-oil-fouling hierarchically structured membranes decorated with urchin-like alpha-FeOOH particles was successfully prepared via the layer-by-layer (LBL) self-assembly method, maintaining numerous effective micro-nanopores. The hierarchical structured membrane exhibited superior superhydrophilicity/underwater superoleophobicity, high water-retention ability, and preferable anti-oil-fouling properties. Furthermore, the biomimetic membrane with controllable pore sizes could not only separate common layered oil/water mixtures but also effectively separate immiscible surfactant-stabilized oil-in-water emulsions of both low-viscosity crude oil and high-viscosity crude oil with an ultrahigh water flux up to 2598.4 L m(-2) h(-1) and an outstanding separation efficiency of 98.5%, revealing its promising prospect in oily wastewater treatment.