Solar-heating superhydrophobic modified melamine sponge for efficient recovery of viscous crude oil

Developing self-heating sorbents for rapid clean-up of viscous oil spills by using clean solar energy is attracting attention. Still, simple and scalable fabrication approaches of solar-heating sorbents remain challenging. Herein, a facile and practical modification strategy was presented to develop a solar-heating modified melamine sponge (rGO/CNT/MS) by dip-coating layer-by-layer (LBL) electrostatic assembly of GO and CNT with opposite charges onto MS skeleton followed by thermal reduction, without any complicated microfabrication and hydrophobic modification processes. Based on the intercalation of CNT into rGO layers and strong conjugation/hyperconjugation synergy of rGO and CNT, the light sorption ability, photothermal conversion, hydrophobicity and mechanical properties of the rGO/CNT/MS sorbent were further improved compared to rGO/MS and CNT/MS. The surface temperature could reach 75 ℃ in 100 s under 1 sun radiation (1 kW m^-2), which would effectively absorb crude oil by in-situ sunlight-heating to reduce its viscosity. The sorption speed increased by about 30 times compared with no sunlight irradiation, and the continuous sorption capacity was up to 1.71 g/cm² at 610 s driven by pump force. The easily-prepared solar-assisted rGO/CNT/MS with high photothermal performance, corrosion resistance, mechanical compressibility, coating firmness and oil sorption ability showed huge potential application in oil spill recovery.