A desert beetle-like mesh membrane by decorating superhydrophilic Fe-doped Cu-MOFs onto superhydrophobic CuC2O4 bowknot-like arrays for boosting water-in-oil emulsion separation

Abstract

Inspired by the water-collecting mechanism of the back structure of the Stenocara beetle, a novel hierarchical structured mesh membrane was rationally constructed by decorating superhydrophilic Fe-doped Cu-MOFs (HKUST-1) onto superhydrophobic CuC2O4 bowknot-like arrays for enhanced separation of oil-in-water emulsions. The Fe-doped HKUST-1 particles, which accumulated in the mesh pores of the superhydrophobic membrane, served as “water-adsorption” centers to facilitate the capture, aggregation, and adsorption of tiny emulsified water droplets. Moreover, the tight packing of Fe-doped HKUST-1 particles within mesh pores not only significantly reduced the pore size, but also extended the effective range of HKUST-1 particles, thereby enhance the “capture-aggregation” process for emulsified water droplets in oil phases. This rationally-designed mesh membrane was demonstrated to efficiently separate water-in-oil emulsions prepared with different oil types, achieving the highest oil permeation flux of approximately 1200 L·m−2·h−1 and maintaining a water content in the oil phase below 57.0 mg·L−1. This study not only presents a simple and scalable strategy for developing a biomimetic anisotropic superwetting mesh membrane, but also underscores its potential industrial applications in oily wastewater treatment.