Scientists from China have invented a carbon-based sponge that can soak up organic pollutants, such as oils and solvents, from the surface of water. No water is absorbed and the sponge can then be wrung out and reused, like an ordinary household sponge. Absorbing up to 180 times its own weight in organic matter, the sponge is light and tough and has the potential to dramatically enhance oil spill cleanup.
This newly invented sponges are made from interconnected carbon nanotubes; tiny, strong and hollow cylinders of interconnected carbon atoms. The tubes are 30 - 50 nanometres across and tens to hundreds of micrometers long . The surface of the tubes is naturally hydrophobic (water-hating), therefore no further modification is needed for the sponges to repel water. At the same time, they love to absorb oil on their surface. As the sponges are over 99% porous or empty, they float on water and there is a lot of room for oil to be absorbed, leading to the extremely high capacity for retention for example, 143 times the sponge's weight for diesel oil and 175 for ethylene glycol.
However, potential applications reach beyond oil spill recovery. According to Researchers, the nanotube sponges can be used as filters, membranes, or absorbents to remove bacteria or contaminants from liquid or gas. They could also be used as noise-absorption layers in houses, and soldiers might benefit by using these sponges in impact energy absorbing components while adding little weight. Thermally insulated clothing is also possible.
Large-scale production is currently being investigated.
This research is published in Scientific Journal Advance Materials, 2009.
Paper is available at www.materialsviews.com/matview/display/en/1220/TEXT
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