Rigid, eco-friendly and superhydrophobic SiO₂-Polyvinyl alcohol composite sponge for durable oil remediation

Development of durable and eco-friendly adsorbents for oil remediation is in great demands. However, most of adsorbents were designed to pursue large capabilities while ignored their strength after adsorbing oil, which might cause secondary oil spilling during complex salvage process. Herein, an eco-friendly and superhydrophobic SiO₂-modified polyvinyl alcohol composite (H-SiO₂-G-PVA) sponge with extraordinary rigid structure after oil adsorption is designed for durable oil remediation. Through a two-step hydrolysis-condensation process including deposition of silica microparticles and introduction of hexadecyltrimethoxysilane (HDTMS), a superhydrophobic H-SiO₂-G-PVA sponge has been successfully constructed. The sponge presents stable superhydrophobicity in various complex environments，therefore it efficiently adsorbs oil from water (up to 6 g g^-1) and separate surfactant-stabilized water/oil emulsion with high efficiency (>99%). Noticeably, the H-SiO₂-G-PVA sponge maintains tough strength (3.5 MPa) after oil adsorption, which ideally overcomes secondary oil spilling problem and endows the sponge with excellent recycling performances (>20 cycles). Meanwhile, the excellent biocompatibility of the sponge (high cell viability of 91.85%) ensures the potential for practical applications. This rigid, eco-friendly oil-adsorbing sponge that achieves stable superhydrophobicity and recyclability, fulfills the application needs for durable oil remediation.