Eco-friendly magneto-photothermal sponge for the fast recovery of highly viscous crude oil spill

The green remediation of crude oil spills is a global concern due to the high viscosity and low fluidity of such oil. Sorbents with heating functions are promising candidates for reducing the viscosity of crude oil and accelerating its cleanup. Herein, we introduce an eco-friendly sponge with the dual functionality of magnetic and photothermal heating for the rapid recovery of heavy oil spills with very high viscosity. The magneto-photothermal sponge was fabricated by the facile dip-coating of magnetoferritin (MPfFn) nanoparticles, polydopamine (PDA), and polydimethylsiloxane (PDMS) on a melamine sponge (MS). The resulting PDMS-MPfFn-MS exhibited excellent hydrophobicity and adequate flame-retardancy. Owing to the electromagnetic–thermal and photothermal conversion properties of the MPfFn/PDA coating, the surface of the functionalized sponge could be rapidly heated to 112.5 °C under alternating magnetic field (f = 502.05 kHz, H = 10.5 kA m⁻¹) or 81.9 °C under light illumination (1 kW m⁻²). The fast and continuous recovery of extremely highly viscous oil was realized by a combination of solar and magnetic heating with a vacuum pump, and the recovery rate reached 50.6 g h⁻¹ cm⁻². The proposed approach integrates the safety and temperature controllability of magnetic heating and the energy-saving feature of solar heating, thereby serving as a new solution for addressing viscous crude oil spills.