Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New pollutant cleanup technique puzzles, pleases chemists

10.09.2003


Scientists looking for ways to clean up a common, persistent type of organic pollutant have developed an approach that not only restores the power of a naturally occurring pollution buster but also boosts it to levels of effectiveness that they can’t currently explain.



"It’s safe to say that we don’t fully understand why this approach works so well, but we’ll take it and develop it and figure out the details as we go," Gerald Meyer, professor of chemistry in the Krieger School of Arts and Sciences at The Johns Hopkins University, said with a laugh.

The targets of the new technique, developed by Sherine Obare, a postdoctoral fellow in Meyer’s lab, are organohalides, a class of compounds used in pesticides, pharmaceuticals, and manufacturing. They pose health risks to humans and have been linked to environmental problems like ozone depletion and climate change.


Obare’s new approach combines an extremely thin film of titanium dioxide with a compound found in life known as hemin. After exposure to ultraviolet light, the hemin and titanium dioxide can break up organohalides at surprisingly high rates. Obare and Meyer will present results of tests of the new approach at 6 p.m. on Sept. 8 in the North Pavillion of the Javits Convention Center in New York at the 226th national meeting of the American Chemical Society.

Seventeen of the top 25 organic groundwater contaminants in urban areas are organohalides, according to a 1997 Environmental Protection Agency report. Organohalides are a class of organic compounds that include a halogen, a group of elements comprised of bromine, fluorine, iodine and chlorine. The compounds are very difficult to break down chemically. Some instances of organohalides in the environment today, for example, can be traced back to the dry cleaning industry of the 1920s and 1930s.

Meyer is director of the National Science Foundation-funded Collaborative Research Activities in Environmental Molecular Sciences (CRAEMS) Center at Johns Hopkins, which is dedicated to finding ways to deal with the environmental effects of organohalides. "These compounds play many important and beneficial roles in the chemical and pharmaceutical industries, so they’re not going away soon, and it’s important that we find ways to minimize their environmental effects," he said.

According to Meyer, scientists have known for decades that hemes, a naturally occurring group of compounds that contain iron atoms, can break up organohalides. The most well-known heme is hemoglobin, a compound in red blood cells that carries oxygen.

"There’s a lot of speculation that hemes in proteins are what cells use to defend themselves from organohalides," Meyer explained. "We can buy hemes – we don’t have to extract them from protein or anything – but when you remove them from their naturally occurring environment, you tend to oxidize them."

In their oxidized state, hemes are no longer useful for breaking down organohalides. Hemes can be re-activated using chemical or electrochemical techniques, but Obare wanted to try using a practical, easily available energy source to power the re-activation: sunlight. She decided to try to take advantage of titanium dioxide’s abilities as a photocatalyst, a substance that promotes chemical reactions in other nearby materials when exposed to light.

"I anchored hemin on porous thin films of nanocrystalline titanium dioxide, and when I exposed the system to light, the hemin was activated to a reduced state where it reacted rapidly with organohalides, producing much better results than I expected," Obare explained. "I’ve even been able to recycle and reactivate the thin films for further organohalide degradation."

Meyer noted that there’s still a lot of development work to be done, not the least of which is figuring out exactly how the chemistry of the new system works. But he speculated that scientists might someday be able to insert a similar system in drinking water – down a well, for example – and power the removal of organohalides with sunlight.


THE JOHNS HOPKINS UNIVERSITY
OFFICE OF NEWS AND INFORMATION
3003 N. Charles Street, Suite 100
Baltimore, Maryland 21218-3843
Phone: 410-516-7160; Fax: 410-516-5251
MEDIA CONTACT: Phil Sneiderman
410-516-7160
prs@jhu.edu

Phil Sneiderman | EurekAlert!
Further information:
http://www.jhu.edu/

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>