Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Water pollutants purged

04.02.2002


Glowing catalyst can spot one part pollutant per million of water
© PhotoDisc


Smart process cleans up contaminated water.

A smart material identifies and destroys toxic pollutants in water. When exposed to the offending molecules, tiny light-emitting zinc oxide particles glow dimly, burn them up, and glow brightly to show they’ve finished1.

The advantage of such an approach, say Prashant Kamat and co-workers at the University of Notre Dame in Indiana, is that the energy-consuming burn-up stage switches on only when pollutants are present.



Kamat’s team is training its cross-hairs on organic aromatic pollutants such as chlorinated phenols. These are used as wood preservatives and pesticides, and are often the by-products of paper pulp milling.

Polychlorinated biphenyls (PCBs) are related substances that are widespread contaminants in industrialized nations. They are used to manufacture paints, plastics, adhesives and electrical goods, and as hydraulic and cooling fluids. Municipal incinerators produce similar chlorinated aromatic compounds called dioxins.

All these chemicals are toxic in high doses, and are possibly carcinogenic.

One widely studied new method for decontaminating water is photocatalytic oxidation: the burning-up of organic molecules in air, stimulated by a light-sensitive catalyst. The most common catalyst in these studies (which have not yet delivered a commercial process) is titanium dioxide.

Zinc oxide might prove more versatile, the Notre Dame group thinks. It destroys organic molecules in much the same way as titanium dioxide, but can also sense the presence of these compounds in the first place.

Zinc oxide is fluorescent: it absorbs ultraviolet light and re-emits the energy as green light. This light level falls by 15% when zinc oxide is exposed to just one part per million of chlorinated aromatic molecules - a few drops in a bath of water.

When such a solution is exposed to strong UV irradiation, a film of zinc oxide particles reacts with the organic molecules, converting them to harmless substances. After several hours of irradiation, the film’s fluorescence increases, because there is less chlorinated compound left.

In a water-purification system, this brightening green light could signal that most of the contaminant has been destroyed, triggering a shutdown of the ultraviolet irradiation.

Whether such a system will be commercially viable depends on whether the contaminants can be removed efficiently and quickly enough.

References

  1. Kamat, P. V., Huehn, R. & Nicolaescu, R. A ’sense and shoot’ approach for photocatalytic degradation of organic contaminants in water. Journal of Physical Chemistry B, 106, 788 - 794, (2002).


PHILIP BALL | © Nature News Service

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

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: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>