Robust self-cleaning urchin-like Ni/Co LDH stainless steel mesh for gravity-driven oil/water emulsion separation and catalytic degradation of aromatic dyes

In the face of frequent oil spills and dye emissions, membrane technology is an efficient method to treat wastewater. However, selectivity, membrane fouling and high operating pressure are tricky problems for practical membrane applications. Hence, it is desirable to design a novel membrane with high selectivity, high flux and superior antifouling properties for gravity-driven separation of complex oily wastewater. In this study, bioinspired by sea urchins with good self-cleaning properties, an urchin-like Ni/Co layered double hydroxide (LDH) surface was grown onto stainless steel mesh (SSM) via a facile hydrothermal method. Due to the unique hierarchical architecture and surface chemistry, Ni/Co@SSM displays a robust self-cleaning oil-repellent ability without hydration. Combining the unique superwettability and highly porous nanostructure, Ni/Co@SSM could be used to separate various oil/water mixtures and emulsions efficiently under only gravity-driven conditions. In addition, Ni/Co@SSM exhibits great catalytic degradation ability of dye solutions in a short time. Notably, Ni/Co@SSM displays excellent physical, chemical and thermal stability in acidic, alkaline and saline environments. Consequently, Ni/Co@SSM possesses broad application prospects with superior self-cleaning and outstanding catalytic degradation ability of aromatic dyes. It shows promising application value in practical complex oily wastewater treatment without complicated operations and chemicals.