Tag Archives: foam

Sponge based on common mattress foam could clean up oil spills

Fireboat response crews battle the blazing remnants of the offshore oil rig Deepwater Horizon in 2010. Credit: Wikimedia Commons/ US Coast Guard.

In 2010, mankind experienced one of the worst environmental disasters in history. The Deepwater Horizon oil spill off the Gulf of Mexico led to the discharge of 4.9 million barrels of oil, causing irreparable damage to the local ecosystem that is still felt to this day. There are, however, thousands of smaller spills that occur every year, but since they’re not that important you never hear about them in the news.

With this huge environmental challenge in mind, researchers at Imperial College London and the University of Toronto have developed a cheap sponge that can soak up oil relatively fast. The best thing about this sponge is that it can also work on wastewater from fracking (up to over 100 billion barrels a of such water are produced each year). At the moment, the toxic fracking byproduct is either injected deep underground or stored in huge tanks.

The team of chemical engineers led by Pavani Cherukupally sought to find a solution by turning to polyurethane foam, a common material used in everyday household items like mattresses. Although polyurethane foam has good oil absorption properties, it only works well under certain conditions of acidity, which can strengthen or weaken the affinity between oil droplets and the sponge.

“It’s all about strategically selecting the characteristics of the pores and their surfaces. Commercial sponges already have tiny pores to capture tiny droplets. Polyurethane sponges are made from petrochemicals, so they have already had chemical groups which make them good at capturing droplets,” said Cherukupally.

“The problem was that we had fewer chemical groups than what was needed to capture all the droplets.”

The researchers developed a coating that alters the foam’s texture, chemistry, and charge, thus making it more suitable for a broad range of situations. When viewed under a microscope, the coating contains hair-like particles of nanocrystalline silicon that act like fishing rods for the oil droplets.

“The critical surface energy concept comes from the world of biofouling research—trying to prevent microorganisms and creatures like barnacles from attaching to surfaces like ship hulls,” Dr. Cherukupally said in a statement.

“Normally, you want to keep critical surface energy in a certain range to prevent attachment, but in our case, we manipulated it to get droplets to cling on tight.”

When tested under four different scenarios of acidity, the coated foam soaked up between 95% and 99% of the oil and did so in no more than three hours.

The material can be washed with a solvent that extracts the oil, crucially allowing the foam to be reused.

Hopefully, this technology will soon become commercially available because, right now, our options are extremely limited and not very effective. For instance, British Petroleum used controversial chemicals called dispersants to clean up the Deepwater Horizon spill by breaking up the oil into smaller drops. The small size of the droplets allows microbes to digest the oil more easily while also emulsifying the oil in the process, harming the ocean ecosystems.

“Current strategies for oil spill cleanup are focused on the floating oil slick, but they miss the microdroplets that form in the water,” said Amy Bilton, a professor at the University of Toronto and co-author of the new study.

“Though our sponge was designed for industrial wastewater, adapting it for freshwater or marine conditions could help reduce environmental contamination from future spills.”

In the future, the researchers would like to use sponges to treat contamination from the gas, mining, and textile industries.

The findings appeared in the journal Nature Sustainability.

Huge waves of foam wash over Froggy Beach after last week’s storm

Stormy weather has an unusual upside if you happen to live on Australia’s eastern coasts: giant waves of sea foam. A video taken a few days after a powerful storm hit Froggy Beach shows a man enjoying this rare phenomenon.

Image via youtube

Big storms or cyclones can sometimes cause the sea to form thick layers of foam according to NOAA, similarly to what you’re used to see in a bathtub rather than in the open ocean.

The foaming is caused by winds and waves stirring the water so proteins, dead algae, and other tiny particles bind together to form longer chemical chains. Grey Leyson captured a stunning video of this phenomenon on Saturday at Froggy’s Beach near Coolangatta, Australia.

While the sea looks inviting enough like this, locals tell that people usually stay away from the ocean after storms as sea snakes have a habit of washing up on the shore.

“The biggest hazard I suppose is sea snakes, there are a lot of sea snakes that get washed in from out further,” Leyson told the Brisbane Times. “You are very unlikely to get bitten by one, but if you do, they are pretty venomous.”

This particular storm brought bigger dangers than a few sea snakes, however. It hit parts of New South Wales with a fury, causing floods and bringing very destructive surfs of over 5 meters (17 feet) on average, reaching up to 12 meters (40 feet) in height.

Thousands of people were forced to evacuate their homes and seek shelter elsewhere as the storm destroyed beachfront properties and brought heavy rains threatening the area around Narrabeen Lakes in Sydney with flooding. Four people died, and three people have been reported missing during the storm, according to the Australian Broadcasting Company.

Conditions over New South Wales and Tasmania improved by Tuesday as the storm passed.

Foamy gold is mostly empty, floats on coffee

Imagine a nugget of real, 20 carat gold floating merrily on the milk foam of your cup of warm cappuccino — scientists from ETH Zurich have found a way to do it. It’s not super-cappuccino, or diamond-strong foam — scientists led by Raffaele Mezzenga, Professor of Food and Soft Materials at ETH have produced a novel foam of gold, a three-dimensional material that is actually mostly…empty.

This 20 carats gold foam is lighter than milk foam.
Image via ethz

“The so-called aerogel is a thousand times lighter than conventional gold alloys. It is lighter than water and almost as light as air,” says Mezzenga.

To the naked eye it looks just like a sturdy, shiny block of conventional gold, but that’s where the resemblance ends — this foamy gold (that’s what I’m calling it) is soft and malleable by hand. It’s 98 percent air held together loosely by gold (four-fifths of the solid material) and milk protein fibrils (one-fifth), qualifying it as 20 carat gold.

The material is created by first heating milk proteins until they coalesce into nanometre-fine fibres named amyloid fibrils. The fibrils are placed in a solution of gold salt, where they interlace into a basic structure that the gold crystallizes on in small particles. The end result is a gel-like gold fibre network.

“One of the big challenges was how to dry this fine network without destroying it,” explains Gustav Nyström, postdoc in Mezzenga’s group and first author of the study.

Air drying wasn’t viable as it could damage the gold structure, so the scientists opted for a gentler but more laborious process that relies on carbon dioxide, assisted by the Professor of Process Engineering Marco Mazzotti.

This method of production, where the metal particles crystallize during the manufacture of the protein scaffold rather than after its completion, is novel. And one of its biggest advantages is that it makes it easy to create a homogeneous gold aerogel that mimics gold alloys perfectly.

It also allows scientists numerous possibilities to influence the properties of the material.

“The optical properties of gold depend strongly on the size and shape of the gold particles,” says Nyström. “Therefore we can even change the colour of the material. When we change the reaction conditions in order that the gold doesn’t crystallise into microparticles but rather smaller nanoparticles, it results in a dark-red gold.”

A foam of amyloid protein filaments without gold (top), with gold microparticles (middle) and gold nanoparticles (below).
Image via ethz

The new material could be used in many of the applications where gold is currently being used, says Mezzenga. The substance’s properties, including its lighter weight, smaller material requirement and porous structure, have their advantages. Applications in watches and jewellery are only one possibility.

Another use demonstrated by the scientists is chemical catalysis: since the highly porous material has a huge surface, chemical reactions that depend on the presence of gold can be run in a very efficient manner. The material could also be used in applications where light is absorbed or reflected. Finally, the scientists have also shown how it becomes possible to manufacture pressure sensors with it.

“At normal atmospheric pressure the individual gold particles in the material do not touch, and the gold aerogel does not conduct electricity,” explains Mezzenga. “But when the pressure is increased, the material gets compressed and the particles begin to touch, making the material conductive.”

Foam gushing off a pint - you either love it or hate it. Credit:

Magnets could help make less foamy beer

There isn’t a less dreaded sight in any respectable bar than a beer bottle gushing foam. It’s not the bartender’s fault though (not necessarily), since different assortments of beer have their signature foam – some make more, some make less. Breweries nowadays use all sorts of anti-foaming agents, and now food scientists in Belgium – the country with the most breweries per capita –  report a novel approach: using magnets.

Science for the greater beer

Foam gushing off a pint - you either love it or hate it. Credit:

Foam gushing off a pint – you either love it or hate it. Credit:

Foam doesn’t necessarily have to be a bad thing. Actually, the two-finger thick foam in a pint is seen a symbol and hallmark of good beer. Guinness, for instance, adds nitrogen to make the foam tastier. When beer foams, it is obviously due to the creation of bubbles. This phenomenon is referred to as nucleation, which is not that well understood. Basically, what happens is a group  of proteins and smaller polypeptides (additional proteins) act as a group and individually as foam positive agents. One particular protein naturally found in barley is Lipid Transfer Protein 1 (LTP1), and it plays a large role in a beer’s foam.

LPT1 is very hydrophobic – it doesn’t like water – so in order to make means, it latches on to CO2 bubles, which are produced during the fermentation process, as well as during the bottling. The protein piggybacks the CO2 and rises to the surface where it forms a coating on the bubbles maintaining the foam. When fungi infect the barley grains in beer’s malt base, these can cause the beer to overfoam. To counter this, brewers add hops extract, an antifoaming agent that binds to the hydrophobic proteins first.

Writing in the  Journal of Food EngineeringBelgian researchers report an ingenious way to reduce foam. They applied a magnetic field to a malt infused with hops extract to disperse the antifoaming agent into tinier particles. Imagine a big sphere and 1,000 other smaller spheres which when joined together form the big sphere. Which of the two has the greatest surface area? That’s the trick. It’s mostly used in chemical applications, especially when working with expensive catalysts like platinum. You break your agent into smaller parts so the surface area is greater, thus reacting more.

The team reports that the smaller particles were much more effective at binding to more hydrophobins, blocking carbon dioxide and decreasing gushing. When the technique was applied to a real brewery, much lower amounts of hops extract were needed to stop foaming. This translates into savings, making the findings of great interest for the beer industry. Future research is needed to determine whether the magnetic field alone is enough to reduce foaming at an industrial scale.