Robust superhydrophobic fluorinated fibrous silica sponge with fire retardancy for selective oil absorption in harsh environment

Water pollution caused by oil leaks is a global environmental problem, calling for high-performance superabsorbent materials for the selective removal and recovery of oil from water. Herein, a robust fluorinated silica fibrous sponge (Silica-GA-F) was developed as an efficient superabsorber for selective oil absorption in harsh environments. Silica fibrous sponge was fabricated by self-assembly electrospinning and calcination. Superhydrophobic Silica-GA-F was obtained after crosslinking and fluorination using glutaraldehyde (GA) and perfluorodecyltriethoxysilane (PDTS). The fluffy microscale fibrous structure and low surface energy of Silica-GA-F contributed to its low bulk density of 16 mg/cm³, relatively high surface area of 6.5 m²/g, and high water contact angle of 151°. The sagging of water interface along silica fiber profile led to an impregnated Cassie-Baxter wetting sate and a “rose petal” effect. The Silica-GA-F possesses an extraordinary absorption capacity of ~122 times of its weight toward various oils, excellent separation efficiency, and promising stability in harsh environments and repetitive use. The oil absorbed can be combusted due to the fire retardancy of Silica-GA-F. Moreover, the GA crosslinking renders the silica sponge with high dimensional stability and recoverability. These properties make the Silica-GA-F sponge an ideal selective superabsorbent material with superior robustness and stability for water remediation, especially in harsh environments.