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Synthetic kitty litter ingredient could have many other applications


July 13, 2011

Scientists have determined the structure of the highly-absorbent mineral used in cat litte...

Scientists have determined the structure of the highly-absorbent mineral used in cat litter, and may now be able to produce a synthetic version that could have many other uses (Photo: abbamouse via Flickr)

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Cat litter might not seem like a particularly exotic substance, but it contains a mineral known as sepiolite, which is actually rather remarkable. Mined from only a few sources worldwide, sepiolite is a type of clay that absorbs 2.5 times its weight in water - that's more absorbent than any other known mineral, or any manmade material. This is made possible by its crystalline structure, that maximizes the amount of internal surface area available for soaking up liquids ... such as cat pee. Recently, an international team of scientists have obtained X-ray diffraction microscope images of sepiolite for the first time. Using the information provided by those images, a cheaper, easier-to-source synthetic version of the mineral could be created, and used in everything from batteries to food.

The images were obtained at the European Synchrotron Radiation Facility (ESRF) in France, using an X-ray beam that measured just 2 by 5 micrometers across. The data was not easy to interpret, however, and needed to be run through computer simulations, where it was cross-referenced with data gathered in electron diffraction experiments conducted at the University Complutense of Madrid.

What the team discovered was that sepiolite is composed of elongated, needle-like crystals, that are packed together quite loosely. Tunnels within those crystals, along with the space between the crystals, serve as a capillary network that draws in liquid. Based on the two sepiolite fibers that were imaged, the total internal surface area of the mineral was found to range between 75 and 400 square meters per gram (90 and 478 squares yards per 0.3 oz). In practical terms, that equals out to 20 grams (0.64 oz) having a total internal surface area equivalent to that of a football field.

"Today, no synthetic clay surpasses natural sepiolite," said Mercedes Suárez from Spain's University of Salamanca. "This is about to change as our understanding of their atomic structure will guide the synthesis of sepiolites from other, more abundant clay minerals and the design of completely new materials for use in catalysis and batteries."

"The future of sepiolites in the household is outside the litterbox," added ESRF's Manuel Sanchez del Rio. "Already today, they absorb liquid spillages and odors and stabilize aqueous products like paints, resins and inks. In synthetic form, they could bind food products and stabilize drugs, extending their shelf life and making sepiolite an edible product."

Also participating in the study was France's Institut Laue-Langevin.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth

Need to be careful when using these types of materials in food products, drugs and construction materials..remember what a miracle material asbestos was in the 60's-80's ? A standard technique in research is to treat a chemical/material as potentially hazardous unless proven otherwise by a suitable test for that purpose of use. Also the internal surface area quoted doesn't sound right, I'm not saying it isn't, just higher than I can visualise!

Good work though.

[See the press release at http://www.esrf.eu/news/general/Sepiolites-diffraction/ - Ed.]

Dewi Owen
14th July, 2011 @ 04:07 am PDT

This stuff reminds me of asbestos. (See the photo with the Euro) I think some serious testing should be done. Carbon nano-tubes ought to be absorbent, but may be too expensive. Charcoal is cheap and has a huge surface area.

14th July, 2011 @ 08:04 am PDT

No wonder they just discovered this... the kitty in the picture does not look ready to give up the secrets of sepiolite.

14th July, 2011 @ 12:38 pm PDT

"sepiolite is a type of clay that absorbs 2.5 times its weight in water - that's more absorbent than any other known mineral, or any manmade material."

That's definitely incorrect. Superabsorbent polymers can absorb hundreds of times their own weight in water.

14th July, 2011 @ 02:38 pm PDT
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