Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cat litter to become an edible product?

13.07.2011
Sepiolites characterized for first time paving way to synthesis

Sepiolite is a lightweight porous mineral used in cat litter and other applications. The extraordinary properties of this clay make it a highly sought after mineral, despite its scarcity in the Earth's crust: only a few mines worldwide extract it, several of them clustered near Madrid in Spain, the world's biggest exporter of this material.

Sepiolite has been known since Roman times when it was used to filter and purify wine, but our understanding at the atomic scale of how these tiny crystals absorb enormous amounts of liquid has remained elusive until now. A team of scientists from Spain and France has obtained for the first time single-crystal X-ray diffraction images of sepiolite, opening the path to industrial synthesis and further improvement of its properties. The results will be published in the October 2011 issue of the journal American Mineralogist.

The team included scientists from the Universities of Madrid and Salamanca in Spain, of the Institut Laue-Langevin (ILL), the European Synchrotron Radiation Facility (ESRF), and the Spanish CRG Beamline at the ESRF (SpLine), all in Grenoble (France).

No other mineral is known to absorb more water or other liquids as efficiently as sepiolites. The reasons are its structural nanoporosity due to tunnels in the crystals, and the fact that the elongated, needle-shaped sepiolite crystals pack very loosely into a lightweight porous material. The surface area ranges between 75 and 400 m2/g, meaning that 20g of mineral have an internal surface equivalent to that of a football court. This is why sepiolite can absorb 2.5 times its weight in water. The tunnels in the crystal structure along with the empty space between the needles form a capillary network through which liquids can easily flow deep inside the bulk where the molecules attach to the surface of the crystals.
The tiny size of these crystals—they measure a few micrometres in length and as little as some dozen atoms across—has been the main obstacle to their being studied with single-crystal diffraction techniques. For this experiment, the scientists collected samples of sepiolite fibres from twenty different deposits around the world. These fibres, each made of many crystals, were first imaged with electron-microscopy and then studied using X-ray powder diffraction.

However, the most accurate technique to resolve the three-dimensional structure of a crystal is single-crystal diffraction with either X-rays or electrons as probe. "To study very small crystals, the ESRF uses an X-ray beam with just 2 by 5 micrometres cross section. In the end, we collected X-ray diffraction data for two fibres", says Manuel Sanchez del Rio from the ESRF, "but the data were not easy to interpret, and needed extensive computer simulations to confirm and refine the information gathered by electron diffraction experiments done in parallel at the University Complutense of Madrid".

The wide variety of sepiolites studied is now enabling the team to correlate between the physical and chemical properties of a given type with its atomic structure. "Today, no synthetic clay surpasses natural sepiolite. 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", says Mercedes Suárez from the University of Salamanca.

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

Reference: Manuel Sanchez del Rio, Emilia Garcia-Romero, Mercedes Suarez, Ivan da Silva, Luis Fuentes Montero, and Gema Martinez-Criado. Variability in sepiolite: Diffraction studies. American Mineralogist (in press). DOI : 10.2138/am.2011.3761.

Claus Habfast | EurekAlert!
Further information:
http://www.esrf.fr

More articles from Materials Sciences:

nachricht Thanks for the memory: NIST takes a deep look at memristors
22.01.2018 | National Institute of Standards and Technology (NIST)

nachricht Let the good tubes roll
19.01.2018 | DOE/Pacific Northwest National Laboratory

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Thanks for the memory: NIST takes a deep look at memristors

22.01.2018 | Materials Sciences

Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments

22.01.2018 | Earth Sciences

Saarland University bioinformaticians compute gene sequences inherited from each parent

22.01.2018 | Life Sciences

VideoLinks Wissenschaft & Forschung
Overview of more VideoLinks >>>