Thermally Conductive and Superhydrophobic Polyurethane Sponge for Solar-Assisted Separation of High-Viscosity Crude...

The rapid and effective separation of high-viscosity heavy crude oil from seawater is a worldwide challenge. Herein, an ultralow density, photothermal, superhydrophobic, and thermally conductive polyurethane/polyaniline/hexagonal boron nitride@Fe₃O₄/polyacrylic-oleic acid resin sponge (PU/PANI/h-BN@Fe₃O₄/AR) was fabricated with a water contact angle (WCA) of 158°, thermal conductivity of 0.76 W m^-1 K^-1, density of 0.038 g cm^-3, limited oxygen index (LOI) of 28.82%, and porosity of 97.97% and used for solar-assisted separation of high-viscosity crude oil from water. Photothermal components were composed of PANI and Fe₃O₄, while h-BN particles were used as thermally conductive and flame retardant fillers. Therefore, the illuminated sunlight irradiation on the modified sponge was converted to heat due to the activity of photothermal components. The produced heat was rapidly transferred to the environment due to the presence of h-BN for increasing the temperature of the high-viscosity crude oil and reducing oil viscosity that helped to promote its fluidity and effective absorption. The crude oil absorption capacity of this sponge increased from 4 to 57 g g^-1 under irradiation of a sunlight simulator (power: 1 sun: 1 kW m^-2) for 17 min due to oil viscosity reduction from 2.46 × 10⁴ to below 100 mPa s followed by an increase in the surface temperature from 26 to 89 °C. Also, the oil absorption capacity was evaluated in a static state (172 g g^-1 for chloroform), under different external magnetic fields (140.7 g g^-1 for gasoline), and in a continuous state, which was 65,100 times of its own weight in the gasoline filtration process. The PU/PANI/h-BN@Fe₃O₄/AR sponge exhibited excellent stability against 20 times of reusing, mechanical compression, abrasion, immersing in various pH solutions, seawater, and high temperature. In all, the results confirmed that the prepared sponge is an excellent absorbent for organic solvents and highly viscous crude oil in the absence and presence of sunlight irradiation.