Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Lasers zap decontaminates from soil

30.08.2017

A recently proposed method using lasers to remove soil contaminants may be cheaper and more efficient than conventional methods

There might be a new and improved way to rid contaminated soil of toxins and pollutants: zap it with lasers. By directly breaking down pollutants, researchers say, high-powered lasers can now be more efficient and cheaper than conventional decontamination techniques.


Laser-induced soil decontamination (A), laser-generated patterns (B and C), and an infrared image of temperature distribution along track of laser movement (D).

Credit: AIP Publishing

"Other methods are either costly, labor intensive, have low efficiency, or take a long time," said Ming Su, an associate professor of chemical engineer at Northeastern University. With two of his graduate students, Wenjun Zheng and Sichao Hou, he has shown how such a laser system could work, describing the proof-of-principle results this week in the Journal of Applied Physics, from AIP Publishing.

The biggest advantage of lasers, Su explained, is that they can be used at the site of decontamination. Many conventional decontamination methods require digging up contaminated soil, hauling it somewhere else to be cleaned, and then returning it -- a process that is expensive and time-consuming.

These methods also have shortcomings in how well they can decontaminate. One of the most popular methods uses water or organic solvents to wash away the pollutants. But oftentimes, washing doesn't eradicate contaminants; it only dilutes them. And even if the soil is clean, you might be left with another problem in contaminated water: The organic solvents can themselves be harmful to people, and the process can create byproducts that become secondary contaminants.

There are ways to decontaminate soil on-site, but they have their own limitations. Soil vapor extraction, in which air is pumped into the ground to remove volatile organic compounds, only works on permeable or homogeneous soils. Biological approaches to break down pollutants using plants or microbes are slow, and only work for low concentrations of certain contaminants.

Lasers, however, can be used on-site to completely break down contaminants. "There is no other method that can do it at such high efficiency," Su said.

To demonstrate that the new method is feasible, the researchers tested it on a simulated soil made from porous silica. They contaminated their artificial soil with a carcinogenic chemical called DDE, which is a product of DDT, the carcinogenic pesticide that was banned in the U.S. in 1972. The DDE molecules fluoresce under ultraviolet light, making them easier to detect.

Almost immediately after shining a high-powered infrared laser on the contaminated artificial soil, the glowing ceased. The lack of fluorescence indicated that the DDE was no longer present.

To remove the harmful substance, the laser light heats up the pollutant locally, reaching temperatures of thousands of degrees Celsius. This heat is sufficient to break the chemical bonds of the pollutant, fragmenting DDE into smaller, safer molecules such as carbon dioxide and water.

In principle, lasers should be able to work on all types of contaminants, from organic compounds to metal ions. But first, Su said, the researchers will have to do more experiments with other contaminants. Future studies also need to involve more careful analysis to determine whether all of the contaminant is, in fact, broken down sufficiently to meet standards.

Eventually, Su envisions a multi-laser system carried on the back of a truck. The laser light, channeled through fiber-optic cables that penetrate the soil, could perhaps couple to a plow that loosens the dirt, better exposing it to the laser light.

###

The article, "Laser induced rapid decontamination of aromatic compound from porous soil simulant," is authored by Wenjun Zheng, Sichao Hou and Ming Su. The article will appear in the Journal of Applied Physics on August 29, 2017 [DOI: 10.1063/1.4985813]. After that date, it can be accessed at http://aip.scitation.org/doi/full/10.1063/1.4985813.

ABOUT THE JOURNAL

Journal of Applied Physics is an influential international journal publishing significant new experimental and theoretical results of applied physics research. See http://jap.aip.org.

Media Contact

Julia Majors
media@aip.org
301-209-3090

 @AIPPhysicsNews

http://www.aip.org 

Julia Majors | EurekAlert!

More articles from Physics and Astronomy:

nachricht MEMS chips get metatlenses
21.02.2018 | American Institute of Physics

nachricht International team publishes roadmap to enhance radioresistance for space colonization
21.02.2018 | Biogerontology Research Foundation

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Researchers invent tiny, light-powered wires to modulate brain's electrical signals

21.02.2018 | Life Sciences

The “Holy Grail” of peptide chemistry: Making peptide active agents available orally

21.02.2018 | Life Sciences

Atomic structure of ultrasound material not what anyone expected

21.02.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>