Fabrication of Robust, Flame-Retardant, and Superhydrophobic Melamine Sponges with SiO2@ZIF-8 Core-Shell Nanoparticles for Highly Efficient Oil/Water Separation

The frequent spills of offshore oil pose a great threat to the ecological environment and human health. Therefore, developing an adsorption material that is efficient, environmentally friendly, and easy to operate in complex environments to replace traditional technologies with low efficiency has become a major challenge in the field of oil-water separation. In this work, a green and superhydrophobic melamine sponge was first developed, inspired by lotus leaves. Then, a core-shell structure of inorganic metal oxide @ metal-organic framework (SiO 2 @ZIF-8) was synthesized by a simple sol-gel method. Finally, the structure was anchored onto the melamine sponge using low-surface-energy polydimethylsiloxane (PDMS), forming a unique hierarchical micro-nano structure. The modified sponge exhibited excellent superhydrophobicity (water contact angle = 156°) and oil adsorption capacity (ranging from 58.5 to 114.3   g/g). It still exhibited perfect mechanical properties, hydrophobicity stability, and thermal stability even under prolonged high temperatures, strong acids/bases, and multiple cycles of extreme compression. Furthermore, the material also demonstrated remarkable flame retardancy, which significantly enhances the safety of the sponge in practical applications. This study provides an efficient and sustainable practical solution for responding to oil spills, with broad application prospects.