A Magnetic Flame‐Retardant Hydrophobic Polyurethane Sponge With Photothermal Effect for Oil–Water Separation

ABSTRACT

The discharge of oil spills and oily wastewater poses serious threats to the natural environment. Developing efficient, reusable, and multifunctional oil sorbents is therefore important for oil–water separation. In this study, polyurethane sponge was used as the substrate, and a magnetic, flame‐retardant, hydrophobic sponge with light‐assisted crude oil uptake was prepared by dip‐coating Fe ₃ O ₄ nanoparticles and polytetrafluoroethylene (PTFE) with a PDMS/TEOS‐derived siloxane network. The modified sponge exhibited an average water contact angle of 149.5°, approaching superhydrophobicity, and showed selective oil sorption behavior. The diesel sorption capacity reached 23.8 g/g and remained 21.2 g/g after 20 sorption–squeezing cycles, although the WCA decreased after recycling. The sponge also demonstrated magnetic controllability and improved flame resistance. Under light irradiation, the crude oil uptake time decreased from 220 s to 100 s, indicating enhanced apparent uptake performance. These results suggest that the PU‐PTFE‐Fe ₃ O ₄ sponge is a promising multifunctional sorbent for oil spill remediation and oily wastewater treatment.