Photothermal and Joule heating-assisted thermal management sponge for efficient cleanup of highly viscous crude oil.

Fast and efficient cleanup of high-viscosity oil spills on the sea is still a global challenge today. Traditional recycling methods are either energy demanding or inefficient. Hydrophobic/oleophilic sorbents are promising candidates to handle oil spills, but they have limited ability to recover high viscosity oil. In this work, we report a superhydrophobic/oleophilic carbon nanotubes (CNT) and polypyrrole (PPy) coated melamine sponge (m-CNT/PPy@MS). The CNT/PPy coating enables the sponge to convert light and electricity to heat, ensuring that the absorbent can adapt to various working environments. The rapid heat generation on the sponge surface can significantly reduce the viscosity of crude oil and accelerate the absorption rate, thereby achieving the purpose of rapid recovery of oil spills. Under one sun illumination (1.0 kW/m2) and an applied voltage (8 V), the surface temperature of the m-CNT/PPy@MS can reach 118.6 °C. The complete penetration time of oil droplets is 93.5% less than that of an unheated sponge. In addition, under half sun irradiation intensity and 11 V, the porous sponge absorbed 6.92kg/m2 of crude oil in the first minute, which is about 31 times as much as that of an unheated sponge. Finally, we demonstrate a continuous absorption system, consisting of a self-heating m-CNT/PPy@MS and peristaltic pump, that can continuously recover oil spills on the sea surface. In view of its unique design, lower cost and fast oil absorption speed, this work provides a new option to tackle large-scale oil spill disasters on the sea surface.