Multifunctional Polydopamine-Modified CuO Nanowire-Haired Membranes for Efficient Oil/Water Separation and Dye Removal

Utilizing the synergistic effect of polydopamine (PD) with functional multigroups and nanowire-haired mesh membrane with a hierarchical structure and high surface area, we designed and fabricated a novel bioinspired PD-wrapped CuO nanowire-haired mesh membrane. The PD ultrathin layer on Cu(OH)2 nanowires, with a thickness ranging from 5 nm to 15 nm, was through controllable self-polymerization of dopamine via catechol chemistry. Successful conversion of Cu(OH)2 to CuO nanowires was achieved through an in situ dehydration process by thermal treatment at 160 degrees C. The as-prepared PD/CuO nanowire-haired mesh membrane exhibited superhydrophilicity and underwater superoleophobicity, demonstrating high oil/water separation efficiency toward various oils with residual oil content of <20 ppm through solely gravity-driven processes. Moreover, the introduction of a PD ultrathin layer on nanowires endowed the PD/CuO nanowire-haired membrane with improved adsorption properties for dyes containing Eschenmoster structures, showing adsorption values almost four times higher than those of the original Cu(OH)2 nanowires-haired membrane without PD wrapping. Our results suggest that the method, combining hierarchical surface structure and functional ultrathin layer, could integrate both oil/water separation and hazardous material adsorption processes for potential wastewater treatment applications.