Semi-IPN hydrogel-modified stainless-steel mesh mixed with SiO₂ is used for oil–water separation

The exceptional oil–water selectivity and low oil adhesion of hydrogel materials have garnered considerable attention within the realm of oil–water separation. In this paper, semi-interpenetrating polymer networks (semi-IPN) were introduced into polyvinyl alcohol (PVA)/polyacrylamide (PAM) hydrogels, which improved the mechanical properties of the hydrogels due to the presence of physical and chemical crosslinking. The incorporation of SiO₂ nanoparticles into the hydrogel improved the surface energy and roughness, which resulted in superhydrophilic and underwater superoleophobic properties of PVA/PAM/SiO₂ semi-IPN hydrogel-coated stainless-steel mesh (SSM). The SSM coated with hydrogel demonstrated excellent resistance to underwater oil, as evidenced by a contact angle of 156°. The oil–water separation flux was as great as 1.2 × 10⁴ L m⁻² h⁻¹, and the separation efficiency exceeded 98%. Furthermore, PVA/PAM/SiO₂ semi-IPN hydrogel-coated SSM is one of the best materials for solving oil–water separation issues due to its recyclability, self-cleaning properties, and stability under acidic and alkaline conditions.