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 New biomaterial could replace plastic laminates, greatly reduce pollution
21.09.2017 | Penn State

nachricht Stopping problem ice -- by cracking it
21.09.2017 | Norwegian University of Science and Technology

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

An international team of physicists a coherent amplification effect in laser excited dielectrics

25.09.2017 | Physics and Astronomy

LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

25.09.2017 | Trade Fair News

Highest-energy cosmic rays have extragalactic origin

25.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>