Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Palladium-gold nanoparticles clean TCE a billion times faster than iron filings

28.06.2012
In the first side-by-side tests of a half-dozen palladium- and iron-based catalysts for cleaning up the carcinogen TCE, Rice University scientists have found that palladium destroys TCE far faster than iron -- up to a billion times faster in some cases.

The results will appear in a new study in the August issue of the journal Applied Catalysis B: Environmental.

TCE, or trichloroethene, is a widely used chemical degreaser and solvent that's found its way into groundwater supplies the world over. The TCE molecule, which contains two carbon atoms and three chlorine atoms, is very stable. That stability is a boon for industrial users, but it's a bane for environmental engineers.

"It's difficult to break those bonds between chlorine and carbon," said study author Michael Wong, professor of chemical and biomolecular engineering and of chemistry at Rice. "Breaking some of the bonds, instead of breaking all the carbon-chlorine bonds, is a huge problem with some TCE treatment methods. Why? Because you make byproducts that are more dangerous than TCE, like vinyl chloride.

"The popular approaches are, thus, those that do not break these bonds. Instead, people use air-stripping or carbon adsorption to physically remove TCE from contaminated groundwater," Wong said. "These methods are easy to implement but are expensive in the long run. So, reducing water cleanup cost drives interest in new and possibly cheaper methods."

In the U.S., TCE is found at more than half the contaminated waste sites on the Environmental Protection Agency's Superfund National Priorities List. At U.S. military bases alone, the Pentagon has estimated the cost of removing TCE from groundwater to be more than $5 billion.

In the search for new materials that can break down TCE into nontoxic components, researchers have found success with pure iron and pure palladium. In the former case, the metal degrades TCE as it corrodes in water, though sometimes vinyl chloride is formed. In the latter case, the metal acts as a catalyst; it doesn't react with the TCE itself, but it spurs reactions that break apart the troublesome carbon-chlorine bonds. Because iron is considerably cheaper than palladium and easier to work with, it is already used in the field. Palladium, on the other hand, is still limited to field trials.

Wong led the development of a gold-palladium nanoparticle catalyst approach for TCE remediation in 2005. He found it was difficult to accurately compare the new technology with other iron- and palladium-based remediation schemes because no side-by-side tests had been published.

"People knew that iron was slower than palladium and palladium-gold, but no one knew quantitatively how much slower," he said.

In the new study, a team including Wong and lead author Shujing Li, a former Rice visiting scholar from Nankai University, China, ran a series of tests on various formulations of iron and palladium catalysts. The six included two types of iron nanoparticles, two types of palladium nanoparticles -- including Wong's palladium-gold particle -- and powdered forms of iron and palladium-aluminum oxide.

The researchers prepared a solution of water contaminated with TCE and tested each of the six catalysts to see how long they took to break down 90 percent of the TCE in the solution. This took less than 15 minutes for each of the palladium catalysts and more than 25 hours for the two iron nanoparticles. For the iron powder, it took more than 10 days.

"We knew from previous studies that palladium was faster, but I think everyone was a bit surprised to see how much faster in these side-by-side tests," Li said.

Wong said the new results should be helpful to those who are trying to compare the costs of conducting large-scale tests on catalytic remediation of TCE.

Additional co-authors include former Rice undergraduate Chris Romanczuk, former Rice graduate student Yu-Lun Fang and faculty members Zhaohui Jin and Tielong Li, both of Nankai University. The research was supported by the National Science Foundation, the Welch Foundation and the China Scholarship Council.

High-resolution images are available for download at: http://news.rice.edu/wp-content/uploads/2012/06/0629_TCE_Water_lg.jpg

CREDIT: Photos.com/Rice University

http://news.rice.edu/wp-content/uploads/2012/06/0629_TCE_Wong_lg.jpg

CAPTION: Michael Wong
CREDIT: Rice University
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is known for its "unconventional wisdom." With 3,708 undergraduates and 2,374 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice has been ranked No. 1 for best quality of life multiple times by the Princeton Review and No. 4 for "best value" among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to www.rice.edu/nationalmedia/Rice.pdf

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

More articles from Studies and Analyses:

nachricht New study shows nanoscale pendulum coupling
05.07.2019 | University of Barcelona

nachricht New unprinting method can help recycle paper and curb environmental costs
26.06.2019 | Rutgers University

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: MOF@SAW: Nanoquakes and molecular sponges for weighing and separating tiny masses

Augsburg chemists and physicists report how they have succeeded in the extremely difficult separation of hydrogen and deuterium in a gas mixture.

Thanks to the Surface Acoustic Wave (SAW) technology developed here and already widely used, the University of Augsburg is internationally recognized as the...

Im Focus: Better thermal conductivity by adjusting the arrangement of atoms

Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.

In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...

Im Focus: First-ever visualizations of electrical gating effects on electronic structure

Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.

Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...

Im Focus: Megakaryocytes act as „bouncers“ restraining cell migration in the bone marrow

Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.

Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

 
Latest News

Hidden dynamics detected in neuronal networks

23.07.2019 | Life Sciences

Towards a light driven molecular assembler

23.07.2019 | Life Sciences

A torque on conventional magnetic wisdom

23.07.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>