David Schiraldi has seen the future and it is clay. The Case Western Reserve University professor and his research team are developing a clay aerogel that transforms common clay into a super lightweight material that could be used as insulating or packing foams, magnets, conductors, and yes, even high tech kitty litter that weighs only 1/10 as much as conventional clay litter.
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Aerogels Coming into Their Own
Aerogels have been around since the 1930’s, when a bet between two scientists resulted in a process for removing the liquid from a gel and replacing it with gas. The gas-replacement process virtually eliminates shrinkage while producing a low density solid material that has extraordinary insulating properties. However, the manufacturing process and high cost of raw materials did not easily lend itself to commercial applications. Recent developments, for example in silica-based aerogel manufacture, are now pointing the way toward a cheaper, less energy intensive process.
Enter Clay Aerogel
As with the original discovery of aerogels, the development of a clay-based aerogel was almost accidental. Cleveland Plain Dealer Science Writer John Mangels describes how one of Schiraldi’s students tried to quick-dry a fresh batch of clay by putting it in a freeze dryer. What came out looked and acted nothing like dried clay. It had turned in to a white fluff, similar to a cotton ball but extremely fragile. Ten years of on-an-off research later, Schiraldi and his students found that the addition of a polymer would give the clay foam what it lacked: strength and flexibility.
Clay Aerogel and Kitty Litter
With millions of cats and other litter-using pets in the U.S. alone, clay litter adds up to one big carbon pawprint. As a greener substitute for conventional clay kitty litter, clay aerogel has two main advantages. It minimizes the use of clay as a raw material, and its significantly lighter weight would reduce greenhouse gas emissions related to the distribution and disposal of conventional clay kitty litter. That’s nothing to sneeze at. Though alternative sustainable materials such as pine pellets are beginning to cut into the kitty litter market, millions of pet owners still depend on less expensive clay litter products, and are not likely to change their habits. An affordable alternative that minimizes clay use is a step in the right direction, and Schiraldi seems confident that the process can be replicated on a commercial scale. His new company, AeroClay Inc., has targeted litter as the first in a full line of clay-based aerogel products.
Clay Aerogel and Sustainability
Though clay and petroleum are both nonrenewable resources, clay does have one major advantage as a more sustainable feedstock for foam insulation and packing material, and that is a far lower risk of environmental damage from spillage, fire, and other industrial accidents. Clay aerogel production may also develop into a commercial scale process with a far lower carbon footprint than petroleum-based foam manufacture. Schiraldi and his team are experimenting with renewable clay aerogel binders, including seaweed protein, plant-bases starches, and waste casein from cheese production. Along similar lines, a researcher in Malaysia has been developing a method for manufacturing silica-based aerogel that uses waste rice husks as a feedstock, reducing production costs by 80%. With potential for everything from cleaning up oil spills to insulating buildings, aerogels are poised to play a significant role in a more sustainable future.
Image: pontman on flickr.com.
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