Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Aerogels Could Clean Contaminated Water, Purify Hydrogen for Fuel Cells

31.07.2007
Scientists at the U.S. Department of Energy's Argonne National Laboratory have identified a new technique for cleansing contaminated water and potentially purifying hydrogen for use in fuel cells, thanks to the discovery of a innovative type of porous material.

Argonne materials scientists Peter Chupas and Mercouri Kanatzidis, along with colleagues at Northwestern and Michigan State universities, created and characterized porous semiconducting aerogels at Argonne's Advanced Photon Source (APS). The researchers then submerged a fraction of a gram of the aerogel in a solution of mercury-contaminated water and found that the gel removed more than 99.99 percent of the heavy metal. The researchers believe that these gels can be used not only for this kind of environmental cleanup but also to remove impurities from hydrogen gas that could damage the catalysts in potential hydrogen fuel cells.

"When people talk about the hydrogen economy, one of the big questions they're asking is ‘Can you make hydrogen pure enough that it doesn't poison the catalyst?'" Chupas said. "While there's been a big push for hydrogen storage and a big push to make fuel cells, there has not been nearly as big a push to find out where the clean hydrogen to feed all that will come from."

The aerogels, which are fashioned from chalcogenides — molecules centered on the elements found directly under oxygen in the periodic table — are expected to be able to separate out the impurities from hydrogen gas much as they did the mercury from the water: by acting as a kind of sieve or selectively permeable membrane. The unique chemical and physical structure of the gels will allow researchers to "tune" their pore sizes or composition in order to separate particular poisons from the hydrogen stream.

"You can put in elements that bind the poisons that are in the stream or ones that bind the hydrogen so you let everything else fall through," Chupas said. For example, gels made with open platinum sites would extract carbon monoxide, a common catalyst poison, he explained.

The research team had not intended to create the aerogels, but their discovery proved fortunate, said Kanatzidis. Originally, the researchers had used surfactants to produce porous semiconducting powders instead of gels. When one of the researchers ran the synthesis reaction without the surfactant, he noticed that gels would form time after time. "When we saw that these chalcogenides would make a gel, we were amazed," said Kanatzidis. "We turned the flask upside down and nothing flowed."

Generally, such reactions produce only uninteresting precipitates at the bottom of the flask, he said, so that in this case, "we knew we had something special."

Kanatzidis and his co-workers recognized that aerogels offered one remarkable advantage over powders: because the material maintained its cohesion, it possessed an enormous surface area. One cubic centimeter of the aerogel could have a surface area as large as a football field, according to Kanatzidis. The bigger the surface area of the material, the more efficiently it can bind other molecules, he said.

Previous experiments into molecular filtration had used oxides rather than chalcogenides as their chemical constituents. While oxides tend to be insulators, most chalcogenides are semiconductors, enabling the study of their electrical and optical characteristics. Kanatzidis hopes to examine the photocatalytic properties of these new gels in an effort to determine whether they can assist in the production, and not merely the filtration, of hydrogen.

Unlike periodic materials, which possess a consistent long-range structure, the gels formed by the Northwestern and Argonne researchers are highly disordered. As a result, conventional crystallographic techniques would not have effectively revealed the structure and behavior of the gels. The high-energy X-rays produced by the APS, however, allowed the scientists to take accurate readings of the atomic distances within these disorganized materials. "This is where the APS really excels. It's the only place that has a dedicated facility for doing these kinds of measurements, and it allows you to wash away a lot of old assumptions about what kinds of materials you can and cannot look at," Chupas said.

The paper, entitled "Porous semiconducting gels and aerogels from chalcogenide clusters," appears in the July 27 issue of Science.

The initial research into porous semiconducting surfactants was supported by a grant from the National Science Foundation. Use of the APS was supported by DOE, Office of Science, Office of Basic Energy Sciences.

With employees from more than 60 nations, Argonne National Laboratory brings the world's brightest scientists and engineers together to find exciting and creative new solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America 's scientific leadership and prepare the nation for a better future. Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.

| newswise
Further information:
http://www.anl.gov/Media_Center/index.html

More articles from Ecology, The Environment and Conservation:

nachricht Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)

nachricht Dune ecosystem modelling
26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA mission surfs through waves in space to understand space weather

25.07.2017 | Physics and Astronomy

Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds

25.07.2017 | Earth Sciences

The dense vessel network regulates formation of thrombocytes in the bone marrow

25.07.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>