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Super-absorbent material soaks up oil spills

In hopes of limiting the disastrous environmental effects of massive oil spills, materials scientists have teamed up to manufacture and test a new material, called a boron nitride nanosheet, that can absorb up to 33 times its weight in oils and organic solvents -- a trait that could make it an important technology for quickly mitigating these costly accidents. The material, which literally absorbs the oil like a sponge, is the result of support from the Australian Research Council and is now ready to be tested by industry after two years of refinement in the laboratory at Deakin's Institute for Frontier Materials (IFM). Oil spills are a global problem and wreak havoc on our aquatic ecosystems, not to mention cost billions of dollars in damage.

This is a boron nitride nanosheet next to spike of a plant

The nanosheet is made up of flakes, which are just several nanometers (one billionth of a meter) in thickness with tiny holes. This form enables the nanosheet to, in effect, increase its surface area per gram to the size of five and a half tennis courts. According to the researchers, turning the powder into a sponge was a big challenge--but an essential step in the process. In 2013 researchers developed the first stage of the material, but it was simply a powder. This powder had absorption capabilities, but powder cannot be simply thrown onto oil -- need to be able to bind that powder into a sponge so that the oil can be soaked up, and also separated from water. The pores in the nanosheets provide the surface area to absorb oils and organic solvents up to 33 times its own weight. Researchers from Drexel's College of Engineering helped to study and functionalize the material, which started as boron nitride powder, commonly called "white graphite." By forming the powder in to atomically thin sheets, the material could be made into a sponge. The mechanochemical technique developed meant it was possible to produce high-concentration stable aqueous colloidal solutions of boron nitride sheets, which could then be transformed into the ultralight porous aerogels and membranes for oil clean-up.

The Drexel team used computational modeling to help understand the intimate details of how the material was formed. In the process, the team learned that the boron nitride nanosheets are flame resistant--which means they could also find applications in electrical and heat insulation. The nanotechnology team at Deakin's Institute for Frontier Materials has been working on boron nitride nanomaterials for two decades and has been internationally recognized for its work in the development of boron nitride nanotubes and nanosheets. This project is the next step in the IFM's continued research to discover new uses for the material.

(Source: Weiwei Lei, Vadym N. Mochalin, Dan Liu, Si Qin, Yury Gogotsi, Ying Chen. Boron nitride colloidal solutions, ultralight aerogels and freestanding membranes through one-step exfoliation and functionalization. Nature Communications, 2015; 6: 8849 DOI:10.1038/NCOMMS9849)