Gravity-based oil spill remediation using reduced graphene oxide/LDPE sheet for both light and heavy oils

Oil spill is a catastrophic accident to environment and human beings, requiring a rapid response to reduce the damage. The conventional oil collecting techniques based on adsorption or filtration, however, are not suitable for rapid response because of their performance dependence on oil types. Here we show that an oil collection technique based on gravity, unlike the conventional schemes based on adsorption or filtration, enables collection of light as well as heavy oils regardless of the viscosity. A solid sheet, which is lighter than water but heavier than oil, would be placed by gravity between oil and water, thereby physically separating oil from water. This fact is utilized to devise a simple and yet efficient oil recovery scheme. The oil on the sheet, over 10 cm in diameter and 0.18 mm in thickness, is drawn into a reservoir by gravity through a 4 mm tube connected to a hole in the center of the sheet. The sheet floating on water can recover oil at a rate of ~1,150,000 L m−2 h−1 that is an order of magnitude higher than that obtainable from filtration methods. We expect this nature-provided oil recovery scheme, which is autonomous, inexpensive, and fast, would provide a quick oil spill remediation regardless of the oil type, thereby minimizing the damage to environment and human beings.