Superhydrophobic palmitic acid modified Cu(OH)2/CuS nanocomposite-coated copper foam for efficient separation of oily wastewater

Developing an efficient, simple, and low-cost oil-water separation technologies is critical to address the challenges of oily wastewater treatment. In this work, a nanoflower-like CuS embedded into Cu(OH)2 nanowire arrays (Cu(OH)2/CuS) were grown on the surfaces of copper foam (CF) by combination of chemical etching and ion exchange methods, and subsequent modification with palmitic acid (PA) was performed to achieve superhydrophobic CF/Cu(OH)2/CuS-PA oil-adsorption materials. The reaction conditions of ion exchange such as the Na2S concentration and immersion time were demonstrated to be key factors to form hierarchical Cu(OH)2/CuS nanowire arrays, and thus further significantly influenced the hydrophobicity of the copper foam. Such superhydrophobic CF/Cu(OH)2/CuS-PA with a static water contact angle of 153.4° delivered a high separation efficiency of oil-water mixtures at 98.8%, and the separation efficiency was always up to 97.6% for various water-in-oil emulsions. After operating successive 30 cycles of oil-water separation, the high separation efficiency remained unchanged. The CF/Cu(OH)2/CuS-PA also presented high stability, good anti-corrosion and mechanical properties in harsh environments. Thus, this superhydrophobic copper foam offers a potentially promising three-dimensional adsorbent for practical application of spill oil recovery and oil/water separation.