Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nano-infused filters prove effective

27.04.2010
Rice scientists build better catalyst with nanotube membranes

Rice University researchers and their colleagues in Finland and Hungary have found a way to make carbon nanotube membranes that could find wide application as extra-fine air filters and as scaffolds for catalysts that speed chemical reactions.

The results reported in the journal ACS Nano show how such filters can remove up to 99 percent of particulates with diameters of less than a micrometer – or a millionth of a meter. (A human hair is about 100 micrometers wide.)

Using chemical vapor deposition (CVD), a team led by Rice's Robert Vajtai, a faculty fellow in mechanical engineering and materials science, created devices that, at the start of the process, look like tiny showerheads. After 30 minutes in the CVD furnace, the laser-created holes in these silicon dioxide templates fill up with a forest of carbon nanotubes through which only particles on the nanometer scale can pass.

When the tubes are functionalized with catalytic chemicals, particles enter one side of the filter in one form and come out as another. The process is similar to that used by catalytic converters in cars, which convert carbon monoxide into a less-toxic mix of carbon dioxide, nitrogen and water.

"Even when the holes are larger than the particle itself, it can be a very effective filter," Vajtai said. "The basic idea is you have this carbon nanotube forest. The gas flows through, and because of the very small distance between the tubes, gas atoms have to hit many of them before they get out the other side.

"This very strong interaction, compared to macroscopic materials and even some microscopic materials, provides a very good way to make a catalyst template or a filter that is much more effective than a HEPA (high-efficiency particulate-absorbing) filter you can buy at the store," he said.

The filters' permeability depends strongly on how long the nanotubes are allowed to grow, which determines their length and density. The team tested the filters' ability to act as catalysts by depositing palladium onto the nanotubes and using them to turn propene into propane, a benchmark test for catalysis. They found the activated membranes "showed excellent and durable activity," according to the paper.

Co-authors of the paper include Pulickel Ajayan, Rice's Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and of chemistry; primary author Niina Halonen, Aatto Rautio, Anne-Riikka Leino, Teemu Kyllönen, Jyrki Lappalainen, Krisztiçn Kordás, Géza Tóth, Mike Huuhtanen and Riitta Keiski of the University of Oulu, Finland; and András Sápi, Mária Szabó, Ákos Kukovecz, Zoltán Kónya and Imre Kiricsi of the University of Szeged, Hungary. Funding came from Rice University, Tekes, the Finnish Funding Agency for Technology and Innovation, and the Academy of Finland.

David Ruth | EurekAlert!
Further information:
http://www.rice.edu

More articles from Materials Sciences:

nachricht Breaking bad metals with neutrons
16.01.2018 | DOE/Argonne National Laboratory

nachricht White graphene makes ceramics multifunctional
16.01.2018 | Rice University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

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...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

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

Gran Chaco: Biodiversity at High Risk

17.01.2018 | Ecology, The Environment and Conservation

Only an atom thick: Physicists succeed in measuring mechanical properties of 2D monolayer materials

17.01.2018 | Physics and Astronomy

Fraunhofer HHI receives AIS Technology Innovation Award 2018 for 3D Human Body Reconstruction

17.01.2018 | Awards Funding

VideoLinks
B2B-VideoLinks
More VideoLinks >>>