Mopping up oil spills with marshmallows(Interesting-Video)!!

Japanese researchers have developed a marshmallow-like material that can mop up hydrocarbons like a sponge and can then be wrung out. The work could one day lead to a cheap and simple solution for cleaning up large oil spills such as one that decimated the Gulf of Mexico in 2010.

Although similar materials have been made before, they have had shortcomings for large-scale clean-up operations including a lack of hydrophobicity, difficult or expensive production methods and an inability to be reused. Now, researchers at Kyoto University have made marshmallow-like macroporous gels that are free from all of these drawbacks.



The team first reported their material in 2011 when they were looking at ways to make transparent and flexible porous aerogels - which are typically solid and rigid - using dimethyldimethoxysilane (DMDMS) together with methyltrimethoxysilane (MTMS).² Unintentionally, they ended up with an opaque material but the team have since discovered that it has remarkable oil-absorbing properties and a wide temperature stability.

 

'We first measured fundamental properties of the porous material, such as density, porosity, pore size and volume, mechanical properties and the surface property,' says co-author Kazuyoshi Kanamori. 'During the course of these measurements, we hit upon the idea of soaking up oils because the marshmallow is hydrophobic and flexible. We tested the separation of hexane and water first and hexane was absorbed completely while the amount of water did not change at all.'

Importantly, the oil can be squeezed out and the material reused. Experiments have also shown that it can work under harsh conditions ranging from 300˚C to -196˚C. However, the team have yet to test the material's performance on highly viscous and complex crude oils.

'We could not test absorption of real crude oil, because crude oils are not easily available,' explains Kanamori. 'We instead tested using a mineral oil that has a viscosity similar to medium crude oil. The kinetics were a bit slow, but there was no problem for absorption.'

Making the marshmallows only requires a simple and inexpensive sol-gel process using reagents that are fairly readily available. However, Kanamori says challenges remain for producing the material in bulk quantities that would be needed for an oil spill.

'You cannot produce a huge amount of the marshmallow by a continuous process,' he says. 'So, in the case where you need huge amounts of the marshmallow for tonnes of oil spilled from an offshore oil well or from a large ship accident, producing the marshmallow in limited time is difficult.'

However, there could be other applications. 'Dealing with oil spills is by no means the only potential application for these materials,' comments Peter Budd a polymer chemistry expert at the University of Manchester, UK.

'There are many situations where there is a need to remove organic compounds from an aqueous medium, including the treatment of wastewater from industrial processes and there is potential to use chemistry to tailor these materials for a wide range of separations.'
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Oil and water: An icy interaction when oil chains are short, steamy when chains are long

Water transforms into a previously unknown structure in between a liquid and a vapor when in contact with alcohol molecules containing long oily chains, according to Purdue University researchers. However, around short oily chains water is more icelike.




Water plays a huge role in biological processes, from protein folding to membrane formation, and it could be that this transformation is useful in a way not yet understood, said Dor Ben-Amotz, the professor of chemistry who led the research.

Ben-Amotz's research team found that as they examined alcohols with increasingly long carbon chains, the transformation occurred at lower and lower temperatures.

When in contact with a chain seven carbon atoms long, the water molecules became much looser and more vaporlike at a temperature of 140 degrees Fahrenheit, which is about halfway between the melting and boiling points.

"For oils with chains longer than four carbons, or about one nanometer in length, we saw the water transform into a completely new structure as the temperature rose," Ben-Amotz said. "If the trend we saw holds true, then this transformation could be happening at body temperature around important physiological molecules like proteins and phospholipids.Water responds very sensitively in its structure to small changes, he said.

"Water's versatility is what makes it so special," he said. "For instance, the surfaces of proteins have both oily and charged regions; and water changes itself to accommodate these very different components and everything in between. We are learning more about exactly how it does this."

The researchers found that water molecules interacting with the oil always formed a more ordered, icelike structure at lower temperatures, while the bulk of the water remained liquid. This ice-like structure would melt away as the temperatures increased and in longer molecules a new structure would appear, he said.

A paper detailing the National Science Foundation-funded work is published in the current issue of Nature and is also highlighted in a news and views article in the same issue. In addition to Ben-Amotz, co-authors include Purdue graduate student Joel Davis and postdoctoral fellows Kamil Gierszal and Ping Wang.

The team's observations add to a more than 70-year debate over the interaction of oil and water, with some studies suggesting that water forms little icebergs around the oil molecules, while others point to a more disordered, vaporlike water structure.

 

"This question was really up for grabs until we introduced an experimental method that could see these subtle changes in water structure," Ben-Amotz said. "Surprisingly, we found that both sides are right, and it depends on the size of the oil."

The challenge of the experiment was that the team needed to see the very small number of water molecules that are in contact with the oil chains in the presence of a very large number of other water molecules.

The team combined Raman scattering and multivariate curve resolution to create an analysis method capable of managing an unprecedented signal-to-noise ratio of 10,000-to-1.

"Most people never take a spectrum with a signal-to-noise ratio greater than 100-to-1, but if we performed this experiment that way we wouldn't see anything," Ben-Amotz said. "We needed to have a higher signal-to-noise ratio because we were looking for a needle in a mountain-sized haystack."

Raman scattering involves shooting a beam of light containing photons into a sample. As the photons hit molecules within the sample, they lose or gain energy. Such measurements create a spectrum of peaks that reveal the vibrational motions of the molecules present in the sample. Shifts in the peaks' shapes can show changes in the strength of bonds between water molecules and whether the molecules are becoming more or less ordered.

"With Raman scattering the bulk of the water creates a mountainous peak in the spectrum that buries everything else," Ben-Amotz said. "Multivariate curve resolution lets us see small changes in water structure under that mountain. As is often the case in science, the key was combining two already established techniques in a new way."

Davis said the team next plans to explore the effects of changes in pH and ionic charges on this transformation with the goal of making the experiments more relevant to proteins and biological systems.

"We are trying to better understand the driving forces of the behavior of proteins and cell membranes that are critical to our health," he said. "The role of water is an important piece of the puzzle."

Note: This story has been adapted from a news release issued by the Purdue University
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