Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tiny particles could solve billion-dollar problem

24.02.2005


Bimetallic nanoparticles break down TCE 100 times faster than bulk catalysts



New research from Rice University’s Center for Biological and Environmental Nanotechnology finds that nanoparticles of gold and palladium are the most effective catalysts yet identified for remediation of one of the nation’s most pervasive and troublesome groundwater pollutants, trichloroethene or TCE. The research, conducted by engineers at Rice and the Georgia Institute of Technology, will appear next month in the journal Environmental Science and Technology, a publication of the American Chemical Society.

"The advantages of palladium-based TCE remediation are well-documented, but so is the cost," said lead researcher Michael Wong, assistant professor of chemical engineering and chemistry at Rice. "Using nanotechnology, we were able to maximize the number of palladium atoms that come in contact with TCE molecules and improve efficiency by several orders of magnitude over bulk palladium catalysts."


TCE, which is commonly used as a solvent to degrease metals and electronic parts, is one of the most common and poisonous organic pollutants in U.S. groundwater. It is found at 60 percent of the contaminated waste sites on the Superfund National Priorities List, and it is considered one of the most hazardous chemicals at these sites because of its prevalence and its toxicity. Human exposure to TCE has been linked to liver damage, impaired pregnancies and cancer.

Cleanup costs for TCE nationwide are estimated in the billions of dollars. The Department of Defense alone estimates the cost of bringing its 1,400 TCE-contaminated sites into EPA compliance at more than $5 billion.

The typical approach to getting rid of TCE involves pumping polluted groundwater to the surface, where it can be exposed to chemical catalysts or microorganisms that break the TCE down into less toxic or non-toxic constituents. In general, chemical catalysis offers faster reactions times than bioremediation schemes but also tends to be more expensive.

One of the major advantages of using palladium catalysts to break down TCE is that palladium converts TCE directly into non-toxic ethane. By contrast, breaking down TCE with more common catalysts, like iron, produces intermediate chemicals, like vinyl chloride, that are more toxic than TCE.

In the CBEN experiments, Wong and collaborators compared the effectiveness of four varieties of palladium catalysts: bulk palladium, palladium powder on an aluminum oxide support base, pure palladium nanoparticles and a hybrid nanoparticle developed by Wong that consists of a gold nanoparticle covered with a thin coat of palladium atoms.

As metal particles get progressively smaller, a higher percentage of the atoms in the particle are found on the surface of the particle instead of being locked away inside the metal where they cannot interact with other chemicals. For example, in the bulk palladium, less than 4 percent of the palladium atoms were on surface of the particle. Pure palladium nanoparticles had 24 percent of the metal on the surface. In the gold-palladium nanoparticles, 100 percent of the palladium atoms are accessible for reaction.

"We’ve documented the efficiency of these catalysts in breaking down TCE, and the next step is engineering a system that will allow us to get at the polluted groundwater," said Joe Hughes, professor of civil and environmental engineering at Georgia Institute of Technology and a co-leader of CBEN’s environmental research programs. "The scale of TCE contamination is enormous, so any new scheme for TCE remediation has got to clean large volumes of water very quickly for a just a few pennies."

Hughes, Wong and their collaborators hope to develop a device that would include a cylindrical pump containing a catalytic membrane of the gold-palladium nanoparticles. The device would be placed down existing wells where it would pump water through continuously, breaking TCE into non-toxic components.

Cost is the primary hurdle to cleaning up TCE-polluted groundwater. CBEN’s team hopes to drive down costs by using every ounce of palladium to maximum efficiency, and by eliminating drilling costs for new wells, construction costs for surface treatment facilities and energy costs of lifting water to the surface.

Nanotechnology is critical to the scheme because only a nanoscale catalyst will be efficient enough to provide the throughput needed to make the whole approach effective. Tests in Wong’s lab have found that the gold-palladium nano-catalysts break TCE down about 100 times faster than bulk palladium catalysts.

Jade Boyd | EurekAlert!
Further information:
http://www.rice.edu

More articles from Ecology, The Environment and Conservation:

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

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: 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...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

Im Focus: Silencing bacteria

HZI researchers pave the way for new agents that render hospital pathogens mute

Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...

Im Focus: Artificial Enzymes for Hydrogen Conversion

Scientists from the MPI for Chemical Energy Conversion report in the first issue of the new journal JOULE.

Cell Press has just released the first issue of Joule, a new journal dedicated to sustainable energy research. In this issue James Birrell, Olaf Rüdiger,...

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

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

19.09.2017 | Event News

New quantum phenomena in graphene superlattices

19.09.2017 | Physics and Astronomy

A simple additive to improve film quality

19.09.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>