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 Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>