Fabrication of a novel multifunctional melamine sponge composite with superhydrophobicity, magnetic drive, flame retardancy, and photothermal effect for high-efficiency oil-water separation

The rising frequency of marine oil spills and industrial oily wastewater discharge necessitates superhydrophobic materials for efficient oil-water separation, environmental resilience, and operational flexibility. Conventional absorption materials suffer from poor cycle stability, limited functionality, and complex preparation. To address these limitations, this study proposes a multifunctional modification strategy using a melamine sponge (MS) substrate. A superhydrophobic MS (SiO 2 -Fe 3 O 4 -PDMS@PDA/MS) was successfully synthesized. Biomimetic polydopamine (PDA) modification created a robust adhesion interface. Synergistic incorporation of SiO 2 nanoparticles and Fe 3 O 4 magnetic particles established a hierarchical rough structure, followed by low surface energy modification with polydimethylsiloxane (PDMS). The material exhibits excellent superhydrophobicity (water contact angle = 153.4°). The strong interfacial adhesion of PDA and the micro-nano structure significantly enhance stability of the coating. Functional advantages include: Magnetic nano-Fe 3 O 4 enables capabilities of directional control for precise absorption of magnetic oil pollutants. The synergy of PDMS and SiO 2 maintains strong hydrophobicity (WCA >142°) after immersion in solutions of acid, alkali, or salt, and mechanical wear. It demonstrates high capacity for absorption of various oils and organic solvents (25.7–72.9 g/g) and efficiency of oil-water separation (98.2%), with a retention rate of performance >83% after 10 cycles. Combined with technology of vacuum-assisted continuous separation, it enhances treatment of complex oil-water systems. Furthermore, the material exhibits characteristics of photothermal conversion, rapidly heating to 110.7 °C under illumination of 1.0 kW/m 2 , significantly boosting absorption capacity for oils of high viscosity. The process of preparation is straightforward and uses environmentally friendly raw materials. Possessing capabilities of magnetic responsiveness, flame retardancy, and photothermal conversion, SiO 2 -Fe 3 O 4 -PDMS@PDA/MS offers an efficient, sustainable solution for recovery of marine oil spills, treatment of industrial oily wastewater, and control of high-viscosity oil pollution.