Fast and selective removal of oils from water surface via highly hydrophobic core-shell Fe₂O₃@C nanoparticles under magnetic field

The removal of oil spills or organic contaminants from water surface is of great technological importance for environmental protection. A major challenge is the fast distribution and collection of absorbent materials with high separation selectivity, good thermal stability, and excellent recyclability. Here we reported fast and selective removal of oils from water surface through core-shell Fe₂O₃@C nanoparticles under magnetic field. These nanoparticles combined with unsinkable, highly hydrophobic and superoleophilic properties, could selectively absorb lubricating oil up to 3.8 times of the particles' weight while completely repelling water. The oil-absorbed nanoparticles were quickly collected in seconds by applying an external magnetic field. More importantly, the oil could be readily removed from the surfaces of nanoparticles by a simple ultrasonic treatment whereas the particles still kept highly hydrophobic and superolephilic characteristics. Experiment results showed that the highly hydrophobic Fe₂O ₃@C nanoparticles could be reused in water-oil separation for many cycles. Our results suggest a facile and efficient method that might find practical applications in the cleanup of oil spills and the removal of organic pollutants on water surface.