Self-Cleaning Material Separates Oil and Water
Oil spills are a constant ecological threat, and like the Deepwater Horizon spill, they can be nightmarish in scope. Scientists are always looking for new and innovative ways to clean up oil spills, including everything from magnetic soap to encouraging the growth of oil-eating microbes.
Now, researchers from Saudi Arabia report the development of another nifty tool: A self-cleaning, hydrophilic (water-loving), superoleophobic (super-oil-hating) material.
The team coated a steel mesh with alternating layers of titanium dioxide and sodium silicate. The resulting material loved water (i.e., became hydrophilic), and after becoming wet, really hated oil (i.e., became superoleophobic). To demonstrate how their material worked, the researchers poured a mixture of water and gasoline over it. (See photo.)
As shown above, the device is able to easily separate water from gasoline. Because the device is water-loving, the water absorbs and passes right through. However, the material hates gasoline; therefore, the gasoline remains stuck at the top, since the material refuses to let it pass through.
Even better, the researchers showed that the material is self-cleaning. If the material becomes contaminated with oils, shining UV light on it will remove them. Titanium dioxide absorbs UV light and can generate reactive oxygen species (such as superoxide and hydroxyl radical). These highly reactive molecules then destroy the oil, removing it from the material.
Source: Lianbin Zhang, Yujiang Zhong, Dongkyu Cha & Peng Wang. "A self-cleaning underwater superoleophobic mesh for oil-water separation." Scientific Reports 3: 2326. Published 31 July 2013. doi:10.1038/srep02326