Nav: Home

KU Leuven researchers use sound waves to prevent small chemical reactors from clogging up

December 18, 2018

Companies are keen to use miniature chemical reactors to make pharmaceuticals and fine chemicals, but are discouraged by their tendency to clog up. Researchers at KU Leuven, Belgium, have now devised an elegant way of using sound waves to keep the chemicals flowing.

The chemical industry conventionally produces in large batches, but this approach has drawbacks. From an environmental point of view, it uses a lot of energy and produces large volumes of waste solvent when the reactors are cleaned. Then there is the cost and inconvenience of storing the chemicals produced until they are needed, or transporting them to where they will be used.

Smaller reactors that produce a continuous flow of the desired chemical product, when and where it is needed, are seen as a much smarter solution. But these miniature reactors, with internal volumes from a couple of microlitres to a couple of millilitres, have a tendency to clog up if particles are produced in the reaction, or required as catalysts.

This is the problem that Professor Simon Kuhn and Dr Zhengya Dong in the Department of Chemical Engineering at KU Leuven set out to solve. Their research, published in the Royal Society of Chemistry journal Lab on a Chip, was carried out in collaboration with the University of Twente in the Netherlands.

It was already known that ultrasound (sound waves with frequencies too high for humans to hear) could be used to move particles around in a liquid. The challenge was to find a way to apply the ultrasound force within the narrow channels of a microreactor.

Their first thought was to use low-frequency ultrasound to shake the clumps of particles apart. "But this is very violent, and heats up the reactor," Professor Kuhn explains. "You form these cavitation bubbles - small liquid-free zones - which destroy your particles, but then they also destroy your reactor."

Their next idea was to use higher frequencies, which, if correctly focused, would push the particles away from the reactor channel walls and stop clogging that way. To achieve this, the reactor had to be very precisely engineered, with channels just half a millimetre wide etched into the surface of a silicon plate that could be integrated with the ultrasound source.

The scientists tested the prototype reactor with calcium carbonate and barium sulphate, which react very strongly and very quickly to form an inorganic salt. This rapidly forms large clumps of particles. While not useful in itself, the salt provides the toughest test possible for the reactor. "If you can do it with these particles, you can do it with anything else."

Not only did the ultrasound keep the product flowing smoothly, forcing the particles into the centre of the channel helped mix them, and so improved the efficiency of the reaction.

The next step is to scale-up the process, although not by making the reactors bigger. "If you can produce a couple of grammes per second, that's already pretty good," Professor Kuhn says. "If you then run a couple of reactors in parallel or in series, you can reach a level of productivity that is interesting for industry."

The study falls within the scope of a basic research grant from the European Research Council (ERC). "While these projects are about fundamental, blue-sky research, we are not just doing research for the sake of it," Professor Kuhn says. "We are developing a technology that is really relevant for industry as well."
-end-


KU Leuven

Related Ultrasound Articles:

World's first ultrasound biosensor created in Australia
Most implantable monitors for drug levels and biomarkers invented so far rely on high tech and expensive detectors such as CT scans or MRI.
Ultrasound can make stronger 3D-printed alloys
A study just published in Nature Communications shows high frequency sound waves can have a significant impact on the inner micro-structure of 3D printed alloys, making them more consistent and stronger than those printed conventionally.
Full noncontact laser ultrasound: First human data
Conventional ultrasonography requires contact with the patient's skin with the ultrasound probe for imaging, which causes image variability due to inconsistent probe contact pressure and orientation.
Ultrasound aligns living cells in bioprinted tissues
Researchers have developed a technique to improve the characteristics of engineered tissues by using ultrasound to align living cells during the biofabrication process.
Ultrasound for thrombosis prevention
Researchers established real-time ultrasonic monitoring of the blood's aggregate state using the in vitro blood flow model.
Ultra ultrasound to transform new tech
A new, more sensitive method to measure ultrasound may revolutionize everything from medical devices to unmanned vehicles.
Shoulder 'brightness' on ultrasound may be a sign of diabetes
A shoulder muscle that appears unusually bright on ultrasound may be a warning sign of diabetes, according to a new study.
Ultrasound-firewall for mobile phones
Mobile phones and tablets through so-called audio tracking, can be used by means of ultrasound to unnoticeably track the behaviour of their users: for example, viewing certain videos or staying in specific rooms and places.
Designing a new material for improved ultrasound
Development of a theoretical basis for ultrahigh piezoelectricity in ferroelectric materials led to a new material with twice the piezo response of any existing commercial ferroelectric ceramics, according to an international team of researchers from Penn State, China and Australia.
Atomic structure of ultrasound material not what anyone expected
Lead magnesium niobate (PMN) is a prototypical
More Ultrasound News and Ultrasound Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Climate Mindset
In the past few months, human beings have come together to fight a global threat. This hour, TED speakers explore how our response can be the catalyst to fight another global crisis: climate change. Guests include political strategist Tom Rivett-Carnac, diplomat Christiana Figueres, climate justice activist Xiye Bastida, and writer, illustrator, and artist Oliver Jeffers.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Speedy Beet
There are few musical moments more well-worn than the first four notes of Beethoven's Fifth Symphony. But in this short, we find out that Beethoven might have made a last-ditch effort to keep his music from ever feeling familiar, to keep pushing his listeners to a kind of psychological limit. Big thanks to our Brooklyn Philharmonic musicians: Deborah Buck and Suzy Perelman on violin, Arash Amini on cello, and Ah Ling Neu on viola. And check out The First Four Notes, Matthew Guerrieri's book on Beethoven's Fifth. Support Radiolab today at Radiolab.org/donate.