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 Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)

nachricht Dune ecosystem modelling
26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

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: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>