Superhydrophobic photothermal sponge based on tannic acid-Fe^3 + coordination complex for high-efficiency viscous oil...

Offshore crude oil spills have caused severe environmental pollution, whereas conventional cleanup methods for high-viscosity crude oil remain inefficient. In this study, a superhydrophobic photothermal sponge (TAFO@MS) with ion-regulated absorption capability was successfully fabricated by loading photothermal particles of TA(Fe³⁺)-APTES onto a melamine sponge (MS) substrate, followed by chemical grafting of hydrophobic octadecylamine (ODA) chains. The final TAFO@MS exhibited exceptional superhydrophobicity with a water contact angle (WCA) of 154.4° ± 1.7° and good photothermal efficiency (80.3 °C/300 s). Through Fe³⁺-modulated synergistic interfacial interactions, the TAFO@MS crude oil absorption rate was enhanced by 7.8 % compared to the unloaded Fe³⁺ sample, and the sponge showed a 60.4-fold improvement in oil absorption performance at room temperature when compared to a commercial polydimethylsiloxane (PDMS)-modified sponge. The oil absorption capacity ranges from 53.1 to 109.8 g/g for various organic liquids, while maintaining 97.5 % oil recovery efficiency during oil-water separation. Notably, the material demonstrated excellent mechanical stability with 96.9 % capacity retention after 50 compression cycles, thereby ensuring reliable performance in practical applications. This study provides a sustainable strategy for marine oil spill remediation that integrates superhydrophobicity, ion-assisted adsorption, and solar-driven photothermal conversion.