Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Sounding out Congo Red

Ultrasound can drain the color from toxic dyes

Brightly colored dyes such as the shimmering Congo Red commonly used in silk clothing manufacture are notoriously difficult to dispose of in an environmentally benign way.

Congo Red is an azo dye, it is toxic to many organisms and is a suspected carcinogen and mutagen. To give it its full name it is the disodium salt of 3,3'-(1E,1'E)-biphenyl-4,4'-diylbis(diazene-2,1-diyl)bis(4-aminonaphthalene-1-sulfonate). It is a benzidine-based anionic disazo dye. Benzidine and Congo Red are, however, banned in many countries because of health concerns. But, it is still widely used in several countries.

Apparently it is used not only to dye silk a gorgeous red, but cleverly adds a second shimmering color and rending the red silk shot through with yellow. It also represents a significant effluent problem along with related dyes from textiles, printing and dyeing, paper, rubber, and plastic industries. Its structural stability makes it highly resistant to biodegradation, and obviously its bright color and toxicity are entirely undesirable in the environment.

Writing in the International Journal of Environment and Waste Management (2008, 2, 309-319), Srinivas Sistla and Suresh Chintalapati, from Hyderabad, India, explain a new approach to degrading Congo Red based on ultrasound.

The researchers point out that advanced oxidation processes (AOP) are currently being developed for remediation of contaminated effluent because they generate no hazardous sludge. Oxidative degradation is based on free radical attack using powerful oxidants. However, Sistla and Chintalapati suggest that sonolysis, break down of an organic compound with ultrasound, has so far been investigated only rarely as an alternative remediation technology. Under well-established 'extreme' conditions, materials irradiated with sound at frequencies around 50 kHz are essentially ripped apart by the formation of free radicals, say the researchers. Carbon dioxide and water are the usual products, although with the case of azo dyes, nitrogen would also feature in the byproducts.

Sonication of Congo Red in the aqueous phase with 50 kHz ultrasound transforms it into a milieu of less toxic intermediates that can then be broken down still further by conventional industrial waste water biodegradation treatment. As a proof of principle, the researchers suggest that the combination of ultrasound and biodegradation could allow the color to be removed from dye-contaminated industrial effluent effectively and the toxicity reduced to negligible levels. "The results obtained from this study revealed the ability of ultrasonic irradiation to transform the aromatic inhibitory compounds to less toxic intermediates, which can be further utilized in aerobic/anaerobic oxidation," the researchers conclude.

Srinivas Sistla | EurekAlert!
Further information:

More articles from Ecology, The Environment and Conservation:

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

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

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: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

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

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>