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 Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

nachricht How to detect water contamination in situ?
22.09.2016 | Tomsk Polytechnic University (TPU)

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: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

ICPE in Graz for the seventh time

20.09.2016 | Event News

 
Latest News

New switch decides between genome repair and death of cells

27.09.2016 | Life Sciences

Nanotechnology for energy materials: Electrodes like leaf veins

27.09.2016 | Physics and Astronomy

‘Missing link’ found in the development of bioelectronic medicines

27.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>