Superhydrophobic and photothermal sponge for effective oil/water separation and solar‐assisted recovery of viscous oil

With the occurrence of offshore oil spills, the recovery of viscous oil continues to be a significant issue. The multi‐functional sponge with superhydrophobic, absorption of high viscosity oil is an effective approach to settle this problem. In this work, the melamine‐formaldehyde (MF) sponge was the backbone and doped with polydopamine (PDA) to mimic mussels. Subsequently, candle soot nanoparticles (CS) and polydimethylsiloxane (PDMS) were applied to modify the MF sponge into a superhydrophobic sponge (P‐CS‐PDA@MF) (WCA = 153.56°). The P‐CS‐PDA@MF sponge showed good absorption properties for many oils and organic solvents (33.87–78.90 times of its own weight). In addition, the P‐CS‐PDA@MF sponge also showed outstanding chemical stability, low density (0.013 g/cm3), emulsion‐breaking ability and flame retardancy. More interestingly, the P‐CS‐PDA@MF sponge showed superior photothermal conversion capability, the temperature of it increased to approximately 91°C within 100 s under simulated sunlight from room temperature (about 25°C), and the sorption capacity of viscous oils was significantly increased. Moreover, the P‐CS‐PDA@MF sponge exhibited a high efficiency (over 97%) for separating viscous oils/water mixtures with the aid of sunlight. This versatile and efficient multifunctional P‐CS‐PDA@MF sponge via a simple and low‐cost way shows promising prospect in oily wastewater treatment and water ecosystem remediation.