AEROGRAPHENE OR GRAPHENE AEROGEL
Aerographene or graphene aerogel was discovered in March 2013 by a team led by Professor Gao Chao at Zhejiang University, China. It is a graphene - based aerogel having a density of 160g/m3 ( 0.0100 lbs / cubic foot), the lighter material after hydrogen, beating helium in the second position, with a density of 0.1786 mg/cm3 .
Until then, the team of Prof. Gao Chao had produced graphene unidimensional fibers and two-dimensional films, but for the aerogel they have developed a third dimension by a new method of lyophilization. The methods used so far, the sol-gel and template oriented methods have some problems, the first can be scaled, but produces poor controllability, whereas the second is limited by the size of the template. Prof. Gao’s team explored a new method -- freeze-drying method: they freeze-dried solutions of carbon nanotubes and graphene to get carbon sponge, this method can be easily scaled and create pieces as large as the templates and wich do not dependent on the container.
The first developed aerogel was also called " frozen smoke " is a colloidal gel-like substance in which the liquid is replaced by gas, can be produced of many different materials, silica, zirconia, carbon ... The first one was created by Samuel Stephens Kistler (1931) as a result of a bet with Charles Learned, in which he had to replace the liquid in a jam jar for gas, keeping the volume of it. Kistler used silicon dioxide for this aerogel. Is highly porous, usually composed of 90.5% to 99.8 % of air, so it has high insulation and absorbent properties.
Aerogels based on different materials have been developing and lowering its density index :
- Aerogel based on silicon dioxide with a density of 1mg/cm3 ( Kistler, 1931)
- Aerogel metallic microgrids based on nickel with 0.9 mg/cm3 density ( HRL Lab - University of California and Technology Calif. Inst ., 2011)
- Aerographite, with a density of 0.18 mg/cm3 ( Kiel Univ and Univ Eng - Harburg Harburg, 2012).
- Aerographene with a density of 0.16 mg/cm3 ( Zhejiang University, 2013).
Using the same example of Professor Sun Haiyan, from the team of Zhejiang Univ, "It's a bit like the large space structures of large stadiums, with steel bars as support and high strength films as the walls to achieve both lightness and strength. Here, carbon nanotubes are the supports and graphene is the wall".
APPLICATIONS FOR OIL SPILL REMEDIATION
According to findings published in the journal "Nature", titled " solid carbon, elastic and lightweight" absorption capacity of this material is amazing, it can suck up to 900 times its own weight in oil at a rate of 68.8 grams per second, but only oil, not water, making it the ideal material for cleaning oil spill cases. Furthermore, after cleaning, the materials, the aerogel, oil and water can be recycled.