Preparation and study of polydopamine-bridged sponge-reinforced hydrophobic silica aerogel for oil-water separation

A polyurethane sponge-reinforced hydrophobic silica aerogel was successfully prepared via a sol-gel method and subsequent ambient-pressure drying using tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) as co-precursors and polydopamine serving as a binder. The obtained sponge composites were characterized in terms of their morphology and physicochemical properties using scanning electron microscopy, N 2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The obtained results indicated that the hydrophobic silica aerogel was successfully anchored onto the polyurethane sponge through the polydopamine-mediated adhesion, resulting in a uniform mesoporous structure throughout the sponge composite. Notably, the sponge composite exhibited excellent hydrophobicity, mechanical properties, and stability under various complex conditions. Moreover, the effects of the TEOS/MTMS precursor composition on the porous structure, surface properties, oil absorption capability, and separation efficiency of the sponge composite were investigated in detail. Using n-hexane as a model oil, the optimized sponge composite exhibited excellent adsorption capacity and separation efficiency for oil-water mixtures and could be reused for at least 30 cycles. These results indicate that the prepared material is suitable for oil-water separation and water purification applications in various complex environments.