Fabrication of superhydrophobic stainless steel mesh with hierarchical micro-nano structures for Oil/Water separation

Conventional superhydrophobic materials for oil–water separation often suffer from poor durability, limited versatility, and environmental concerns arising from fluorine-containing components. To address these drawbacks, this study reports a fluorine-free superhydrophobic stainless steel mesh (ODA‑NS/MUF‑SH‑SSM) fabricated using natural nano‑soil (NS) as a green, roughness-enhancing component, representing a key environmentally friendly breakthrough. The mesh was prepared through two simple steps: spray‑coating with NS/melamine‑urea‑formaldehyde resin (NS/MUF) to construct a micro‑nano rough structure, followed by grafting octadecyl acrylate (ODA) to reduce the surface energy. Characterizations, including SEM, FTIR, EDS, and XPS, confirmed successful surface functionalization. The modified mesh exhibited a water contact angle >160°, rapid oil permeation within 0.4 s, and separation efficiencies >98% for various oil–water mixtures over 100 cycles. Durability tests showed that it retained a contact angle >140° after 100 friction cycles under a 200 g load. This fluorine‑free, natural nano‑soil‑based design aligns with environmental sustainability while overcoming key limitations of traditional superhydrophobic materials, thereby enhancing practical applicability.