Superhydrophobic silicone-coating on carbon foam for efficient oil adsorption

Herein, a one-step solvent-free hydrophobic coating using vapour deposition of poly(dimethyl siloxane) (PDMS) oil on carbon foam, prepared by carbonization of flexible polyurethane foam is reported. The silicone-coating was found to be uniform on the foam surface and the coated foam exhibited superhydrophobic behaviour with a striking water contact angle (WCA) reaching up to ∼ 173°, when the coating was performed at 320 °C for 14 h, from ∼ 106° for uncoated foam. The hydrophobicity showed dependency on the coating temperature and time. The coated foam efficiently adsorbed solvent/oil from oil-water mixture in batch experiments and separated water from oil-water emulsion continuously with a flux of ∼ 7.3 × 105 L m−3h−1 gravitationally with an efficiency of ∼ 98%. The coated CF showed excellent repeatability of oil adsorption and could even adsorb oil in harsh environments.