Category Archives: water

Canadian nano business news: international subsidiary (Nanex) opens in Québec and NanoStruck’s latest results on recovering silver from mine tailings

The Canadian nano business sector is showing some signs of life. Following on my Sept. 3, 2014 posting about Nanotech Security Corp.’s plans to buy a subsidiary business, Fortress Optical Features, there’s an international subsidiary of Nanex (a Belgium-based business) planning to open in the province of Québec and NanoStruck (an Ontario-based company) has announced the results of its latest tests on cyanide-free recovery techniques.

In the order in which I stumbled across these items, I’m starting with the Nanex news item in a Sept. 3, 2014 posting on the Techvibes blog,

Nanex, a Belgian-based innovator and manufacturer of superhydrophobic nanotechnology products, announced last week the creation of its first international subsidiary.

Nanex Canada will be headquartered in Montreal.

For those unfamiliar with the term superhydrophobic, it means water repellent to a ‘super’ degree. For more information the properties of superhydrophobic coatings, the Techvibes post is hosting a video which demonstrates the coating’s properties (there’s a car which may never need washing again).

An Aug. 1, 2014 Nanex press release, which originated the news item, provides more details,

… Nanex Canada Incorporated will be starting operations on October 1st, 2014 and will be headquartered in Montreal, Quebec.

“Nanex’s expansion into Canada is a tremendous leap forward in our international operations, creating not only more efficient and direct channels into all of North America, but also providing access to a new top-notch intellectual pool for our R&D efforts,” Said Boyd Soussana, National Marketing Director at Nanex Canada. “We feel that Quebec and Canada have a great reputation as leaders in the field of advanced technologies, and we are proud to contribute to this scientific landscape.”

Upon launch, Nanex Canada Inc. will begin with retail and sales of its nanotechnology products, which have a wide range of consumer applications. Formal partnerships in B2B [business-to-business] further expanding these applications have been in place throughout Canada beginning in August of 2014. Through its Quebec laboratories Nanex Canada Inc. will also be pursuing R&D initiatives, in order to further develop safe and effective nano-polymers for consumer use, focusing entirely on ease of application and cost efficiency for the end consumer. In addition application of nano-coatings in green technologies will be a priority for North American R&D efforts.

Nanex Company currently manufactures three lines of products: Always Dry, Clean & Coat, and a self-cleaning coating for automotive bodies. These products contain proprietary nano-polymers that when sprayed upon a surface provide advanced abilities including super hydrophobic (extremely water-repellent), oleophobic (extremely oil repellent), and scratch resistance as well as self-cleaning properties.

 

The second piece of news is featured in a Sept. 5, 2014 news item on Azonano,

NanoStruck Technologies Inc. is pleased to announce positive results from test work carried out on silver mine tailings utilizing proprietary cyanide free recovery technologies that returned up to 87.6% of silver from samples grading 56 grams of silver per metric ton (g/t).

A Sept. 4, 2014 NanoStruck news release, which originated the news item, provides more details,

Three leach tests were conducted using the proprietary mixed acid leach process. Roasting was conducted on the sample for two of the leach tests, producing higher recoveries, although the un-roasted sample still produced a 71% recovery rate.

87.6% silver recoveries resulted from a 4 hour leach time at 95 degrees Celsius, with the standard feed grind size of D80 175 micron of roasted material.
84.3% recoveries resulted from a 4 hour leach at 95 degrees Celsius with the standard feed grind size of D80 175 micron with roasted material at a lower acid concentration.
71% recoveries resulted from a 4 hour leach at 95 degrees Celsius from received material, with the standard feed grind size of D80 175 micron with an altered acid mix concentration.

The average recovery for the roasted samples was 86% across the two leach tests performed using the proprietary process.

Bundeep Singh Rangar, Interim CEO and Chairman of the Board, said: “These results further underpin the effectiveness of our processing technology. With our patented process we are achieving excellent recoveries in not only silver tailings, but also gold tailings as well, both of which have vast global markets for us.”

The proprietary process combines a novel mixed acid leach with a solvent extraction stage, utilizing specific organic compounds. No cyanide is used in this environmentally friendly process. The flow sheet design is for a closed loop, sealed unit in which all chemicals are then recycled.

Previous test work undertaken on other gold mine tailings utilizing the proprietary process resulted in a maximum 96.1% recovery of gold. Previous test work undertaken on other silver tailings resulted in a maximum 86.4% recovery of silver.

The technical information contained in this news release has been verified and approved by Ernie Burga, a qualified person for the purpose of National Instrument 43-101, Standards of Disclosure for Mineral Projects, of the Canadian securities administrators.

Should you choose to read the news release in its entirety, you will find that no one is responsible for the information should anything turn out to be incorrect or just plain wrong but, like Nanotech Security Corp., (as I noted in my Sept. 4, 2014 posting), the company is very hopeful.

I have mentioned NanoStruck several times here:

March 14, 2014 posting

Feb. 19, 2014 posting

Feb. 10, 2014 posting

Dec. 27, 2013 posting

New ways to think about water

This post features two items about water both of which suggest we should reconsider our ideas about it. This first item concerns hydrogen bonds and coordinated vibrations. From a July 16 2014 news item on Azonano,

Using a newly developed, ultrafast femtosecond infrared light source, chemists at the University of Chicago have been able to directly visualize the coordinated vibrations between hydrogen-bonded molecules — the first time this sort of chemical interaction, which is found in nature everywhere at the molecular level, has been directly visualized. They describe their experimental techniques and observations in The Journal of Chemical Physics, from AIP [American Institute of Physics] Publishing.

“These two-dimensional infrared spectroscopy techniques provide a new avenue to directly visualize both hydrogen bond partners,” said Andrei Tokmakoff, the lab’s primary investigator. “They have the spectral content and bandwidth to really interrogate huge parts of the vibrational spectrum of molecules. It’s opened up the ability to look at how very different types of vibrations on different molecules interact with one another.”

A July 15, 2014 AIP news release by John Arnst (also on EurekAlert), which originated the news item, provides more detail,

Tokmakoff and his colleagues sought to use two-dimensional infrared spectroscopy to directly characterize structural parameters such as intermolecular distances and hydrogen-bonding configurations, as this information can be encoded in intermolecular cross-peaks that spectroscopy detects between solute-solvent vibrations.

“You pluck on the bonds of one molecule and watch how it influences the other,” Tokmakoff said. “In our experiment, you’re basically plucking on both because they’re so strongly bound.”

Hydrogen bonds are typically perceived as the attractive force between the slightly negative and slightly positive ends of neutrally-charged molecules, such as water. While water stands apart with its unique polar properties, hydrogen bonds can form between a wide range of molecules containing electronegative atoms and range from weakly polar to nearly covalent in strength. Hydrogen bonding plays a key role in the action of large, biologically-relevant molecules and is often an important element in the discovery of new pharmaceuticals.

For their initial visualizations, Tokmakoff’s group used N-methylacetamide, a molecule called a peptide that forms medium-strength hydrogen-bonded dimers in organic solution due to its polar nitrogen-hydrogen and carbon-oxygen tails. By using a targeted three-pulse sequence of mid-infrared light and apparatus described in their article, Tokmakoff’s group was able to render the vibrational patterns of the two peptide units.

“All of the internal vibrations of hydrogen bonded molecules that we look at become intertwined, inextricably; you can’t think of them as just a simple sum of two parts,” Tokmakoff said.

More research is being planned while Tokmakoff suggests that water must be rethought from an atomistic perspective (from the news release),

Future work in Tokmakoff’s group involves visualizing the dynamics and structure of water around biological molecules such as proteins and DNA.

“You can’t just think of the water as sort of an amorphous solvent, you really have to at least on some level think of it atomistically and treat it that way,” Tokmakoff said. “And if you believe that, it has huge consequences all over the place, particularly in biology, where so much computational biology ignores the fact that water has real structure and real quantum mechanical properties of its own.”

The researchers have provided an illustration of hydrogen’s vibrating bonds,

The hydrogen-bonding interaction causes the atoms on each individual N-methylacetamide molecule to vibrate in unison. CREDIT: L. De Marco/UChicago

The hydrogen-bonding interaction causes the atoms on each individual N-methylacetamide molecule to vibrate in unison.
CREDIT: L. De Marco/UChicago

Here’s a link to and a citation for the paper,

Direct observation of intermolecular interactions mediated by hydrogen bonding by Luigi De Marco, Martin Thämer, Mike Reppert, and Andrei Tokmakoff. J. Chem. Phys. 141, 034502 (2014); http://dx.doi.org/10.1063/1.4885145

This paper is open access. (I was able to view the entire HTML version.)

A July 15, 2014 University of Southampton press release on EurekAlert offers another surprise about water,

University of Southampton researchers have found that rainwater can penetrate below the Earth’s fractured upper crust, which could have major implications for our understanding of earthquakes and the generation of valuable mineral deposits.

The reason that water’s ability to penetrate below the earth’s upper crust is a surprise (from the news release),

It had been thought that surface water could not penetrate the ductile crust – where temperatures of more than 300°C and high pressures cause rocks to flex and flow rather than fracture – but researchers, led by Southampton’s Dr Catriona Menzies, have now found fluids derived from rainwater at these levels.

The news release also covers the implications of this finding,

Fluids in the Earth’s crust can weaken rocks and may help to initiate earthquakes along locked fault lines. They also concentrate valuable metals such as gold. The new findings suggest that rainwater may be responsible for controlling these important processes, even deep in the Earth.

Researchers from the University of Southampton, GNS Science (New Zealand), the University of Otago, and the Scottish Universities Environmental Research Centre studied geothermal fluids and mineral veins from the Southern Alps of New Zealand, where the collision of two tectonic plates forces deeper layers of the earth closer to the surface.

The team looked into the origin of the fluids, how hot they were and to what extent they had reacted with rocks deep within the mountain belt.

“When fluids flow through the crust they leave behind deposits of minerals that contain a small amount of water trapped within them,” says Postdoctoral Researcher Catriona, who is based at the National Oceanography Centre. “We have analysed these waters and minerals to identify where the fluids deep in the crust came from.

“Fluids may come from a variety of sources in the crust. In the Southern Alps fluids may flow upwards from deep in the crust, where they are released from hot rocks by metamorphic reactions, or rainwater may flow down from the surface, forced by the high mountains above. We wanted to test the limits of where rainwater may flow in the crust. Although it has been suggested before, our data shows for the first time that rainwater does penetrate into rocks that are too deep and hot to fracture.”

Surface-derived waters reaching such depths are heated to over 400°C and significantly react with crustal rocks. However, through testing the researchers were able to establish the water’s meteoric origin.

Funding for this research, which has been published in Earth and Planetary Science Letters, was provided by the Natural Environmental Research Council (NERC). Catriona and her team are now looking further at the implications of their findings in relation to earthquake cycles as part of the international Deep Fault Drilling Project [DFDP], which aims to drill a hole through the Alpine Fault at a depth of about 1km later this year.

Here’s a link to and a citation for the paper,

Incursion of meteoric waters into the ductile regime in an active orogen by Catriona D. Menzies, Damon A.H. Teagle, Dave Craw, Simon C. Cox, Adrian J. Boyce, Craig D. Barrie, and Stephen Roberts. Earth and Planetary Science Letters Volume 399, 1 August 2014, Pages 1–13 DOI: 10.1016/j.epsl.2014.04.046

Open Access funded by Natural Environment Research Council

This is the first time I’ve seen the funding agency which made the paper’s open access status possible cited.

Fewer silver nanoparticles washed off coated textiles

This time I have two complementary tidbits about silver nanoparticles, their use in textiles, and washing. The first is a June 30, 2014 news item on Nanowerk, with the latest research from Empa (Swiss Federal Laboratories for Materials Science and Technology) on silver nanoparticles being sloughed off textiles when washing them,

The antibacterial properties of silver-coated textiles are popular in the fields of sport and medicine. A team at Empa has now investigated how different silver coatings behave in the washing machine, and they have discovered something important: textiles with nano-coatings release fewer nanoparticles into the washing water than those with normal coatings …

A June 30,  2014 Empa news release, which originated the news item, describes the findings in more detail,

If it contains ‘nano’, it doesn’t primarily leak ‘nano’: at least that’s true for silver-coated textiles, explains Bernd Nowack of the «Technology and Society» division at Empa. During each wash cycle a certain amount of the silver coating is washed out of the textiles and ends up in the waste water. [emphasis mine] Empa analysed this water; it turned out that nano-coated textiles release hardly any nano-particles. That’s quite the opposite to ordinary coatings, where a lot of different silver particles were found. Moreover, nano-coated silver textiles generally lose less silver during washing. This is because considerably less silver is incorporated into textile fabrics with nano-coating, and so it is released in smaller quantities for the antibacterial effect than is the case with ordinary coatings. A surprising result that has a transformative effect on future analyses and on the treatment of silver textiles. «All silver textiles behave in a similar manner – regardless of whether they are nano-coated or conventionally-coated,» says Nowack. This is why nano-textiles should not be subjected to stricter regulation than textiles with conventional silver-coatings, and this is relevant for current discussions concerning possible special regulations for nano-silver.

But what is the significance of silver particles in waste water? Exposed silver reacts with the (small quantities of) sulphur in the air to form silver sulphide, and the same process takes place in the waste water treatment plant. The silver sulphide, which is insoluble, settles at the bottom of the sedimentation tank and is subsequently incinerated with the sewage sludge. So hardly any of the silver from the waste water remains in the environment. Silver is harmless because it is relatively non-toxic for humans. Even if silver particles are released from the textile fabric as a result of strong sweating, they are not absorbed by healthy skin.

I’ve highlighted Nowack’s name as he seems to have changed his opinions since I first wrote about his work with silver nanoparticles in textiles and washing in a Sept. 8, 2010 posting,

“We found that the total released varied considerably from less than 1 to 45 percent of the total nanosilver in the fabric and that most came out during the first wash,” Bernd Nowack, head of the Environmental Risk Assessment and Management Group at the Empa-Swiss Federal Laboratories for Materials Testing and Research, tells Nanowerk. “These results have important implications for the risk assessment of silver textiles and also for environmental fate studies of nanosilver, because they show that under certain conditions relevant to washing, primarily coarse silver-containing particles are released.”

How did the quantity of silver nanoparticles lost in water during washing change from “less than 1 to 45 percent of the total nanosilver in the fabric” in a 2010 study to “Empa analysed this water; it turned out that nano-coated textiles release hardly any nano-particles” in a 2014 study? It would be nice to find out if there was a change in the manufacturing process and whether or not this is global change or one undertaken in Switzerland alone.

Here’s a link to and a citation for the Empa paper,

Presence of Nanoparticles in Wash Water from Conventional Silver and Nano-silver Textiles by Denise M. Mitrano, Elisa Rimmele, Adrian Wichser, Rolf Erni, Murray Height, and Bernd Nowack. ACS Nano, Article ASAP DOI: 10.1021/nn502228w Publication Date (Web): June 18, 2014

Copyright © 2014 American Chemical Society

This paper is behind a paywall.

The second tidbit is from Iran and may help to answer my questions about the Empa research. According to a July 7, 2014 news item on Nanowerk (Note: A link has been removed),

Writing in The Journal of The Textile Institute (“Effect of silver nanoparticles morphologies on antimicrobial properties of cotton fabrics”), researchers from Islamic Azad University in Iran, describe the best arrangement for increasing the antibacterial properties of textile products by studying various structures of silver nanoparticles.

A July 7, 2014 news release from the Iran Nanotechnology Initiative Council (INIC), which originated the news item, provides more details,

By employing the structure presented by the researchers, the amount of nanoparticles stabilization on the fabric and the durability of its antibacterial properties increase after washing and some problems are solved, including the change in the fabric color.

Using the results of this research creates diversity in the application of various structures of nanoparticles in the complementary process of cotton products. Moreover, the color of the fabric does not change as the amount of consumed materials decreases, because the excess use of silver was the cause of this problem. On the other hand, the stability and durability of nanoparticles increase against standard washing. All these facts result in the reduction in production cost and increase the satisfaction of the customers.

The researchers have claimed that in comparison with other structures, hierarchical structure has much better antibacterial activity (more than 91%) even after five sets of standard washing.

This work on morphology would seem to answer my question about the big difference in Nowack’s description of the quantity of silver nanoparticles lost due to washing. I am assuming, of course, that something has changed with regard to the structure and/or shape of the silver nanoparticles coating the textiles used in the Empa research.

Getting back to the work in Iran, here’s a link to and a citation for the paper,

Effect of silver nanoparticles morphologies on antimicrobial properties of cotton fabrics by Mohammad Reza Nateghia & Hamed Hajimirzababa. The Journal of The Textile Institute Volume 105, Issue 8, 2014 pages 806-813 DOI: 10.1080/00405000.2013.855377 Published online: 21 Jan 2014

This paper is behind a paywall.

UNESCO course: Nanotechnology for Water and Wastewater Treatment 2015 call for applications

Despite an initially puzzling announcement from UNESCO (United Nations Educational, Scientific, and Cultural Organization), I was able to track down a description for the course on studyfinder.nl,

Nanotechnology for Water and Wastewater Treatment

UNESCO-IHE Institute for Water Education

Certificate / Diploma Short course Delft [Netherlands]

Field of study     Agriculture and environment
Course description     The course overviews the state-of-the-art and novel developments of nanotechnology in applications for drinking water production and wastewater treatment.
Study subjects     Framework: Nanoparticles and Water; Environmental Fate; Risk Analysis. Nanotechnology for Water/Wastewater Treatment: Physical, Chemical and Biological Properties of Nanoparticles. High-Performance Water and Wastewater Purification Systems: Nanofiltration, Nanosorbents and Nanocatalysts. Nanoparticles that Sense and Treat Disease: Biosensors and Desinfectants.
Course objectives     Apply innovative applications of nanotechnology in drinking water production and wastewater treatment. Familiar with the state-of-the-art, impact and cost-benefit analysis of nanotechnology processes for water and wastewater treatment. Communicate successfully on nanoscience and nanotechnology interfacing with environmental chemistry, environmental engineering and bioprocess.

Duration     2 weeks full-time
Language of instruction     English

There is a bit more information on the UNESCO website’s Short Courses Nanotechnology for Water and Wastewater Treatment webpage,

The emergence of nanobiotechnology and the incorporation of living microorganisms in biomicroelectronic devices are revolutionizing interdisciplinary opportunities for microbiologists and biotechnologists to participate in understanding microbial processes in and from the environment. Moreover, it offers revolutionary perspectives to develop and exploit these processes in completely new ways.

This short course presents an opportunity to learn and discuss about various innovative research aspects of nanoscience and nanotechnology interfacing with environmental chemistry, environmental engineering and bioprocess technology amongst professionals as well as young researchers and PhD students.

You can access the 2015 call for applications on this UNESCO webpage. For more information contact,

Piet Lens

Professor of Environmental Biotechnology

Phone +31152151816
Email

Harvest water from desert air with carbon nanotube cups (competition for NBD Nano?)

It’s been a while since I’ve seen Pulickel Ajayan’s name in a Rice University (Texas) news release and I wonder if this is the beginning of a series. I’ve noticed that researchers often publish a series of papers within a few months and then become quiet for two or more years as they work in their labs to gather more information.

This time the research from Pulickel’s lab has focused on the use of carbon nanotubes to harvest water from desert air. From a June 12, 2014 news item on Azonano,

If you don’t want to die of thirst in the desert, be like the beetle. Or have a nanotube cup handy.

New research by scientists at Rice University demonstrated that forests of carbon nanotubes can be made to harvest water molecules from arid desert air and store them for future use.

The invention they call a “hygroscopic scaffold” is detailed in a new paper in the American Chemical Society journal Applied Materials and Interfaces.

Researchers in the lab of Rice materials scientist Pulickel Ajayan found a way to mimic the Stenocara beetle, which survives in the desert by stretching its wings to capture and drink water molecules from the early morning fog.

Here’s more about the research from a June 11, 2014 Rice University news release (by Mike Williams?), which originated the news item,

They modified carbon nanotube forests grown through a process created at Rice, giving the nanotubes a superhydrophobic (water-repelling) bottom and a hydrophilic (water loving) top. The forest attracts water molecules from the air and, because the sides are naturally hydrophobic, traps them inside.

“It doesn’t require any external energy, and it keeps water inside the forest,” said graduate student and first author Sehmus Ozden. “You can squeeze the forest to take the water out and use the material again.”

The forests grown via water-assisted chemical vapor deposition consist of nanotubes that measure only a few nanometers (billionths of a meter) across and about a centimeter long.

The Rice team led by Ozden deposited a superhydrophobic layer to the top of the forest and then removed the forest from its silicon base, flipped it and added a layer of hydrophilic polymer to the other side.

In tests, water molecules bonded to the hydrophilic top and penetrated the forest through capillary action and gravity. (Air inside the forest is compressed rather then expelled, the researchers assumed.) Once a little water bonds to the forest canopy, the effect multiplies as the molecules are drawn inside, spreading out over the nanotubes through van der Waals forces, hydrogen bonding and dipole interactions. The molecules then draw more water in.

The researchers tested several variants of their cup. With only the top hydrophilic layer, the forests fell apart when exposed to humid air because the untreated bottom lacked the polymer links that held the top together. With a hydrophilic top and bottom, the forest held together but water ran right through.

But with a hydrophobic bottom and hydrophilic top, the forest remained intact even after collecting 80 percent of its weight in water.

The amount of water vapor captured depends on the air’s humidity. An 8 milligram sample (with a 0.25-square-centimeter surface) pulled in 27.4 percent of its weight over 11 hours in dry air, and 80 percent over 13 hours in humid air. Further tests showed the forests significantly slowed evaporation of the trapped water.

If it becomes possible to grow nanotube forests on a large scale, the invention could become an efficient, effective water-collection device because it does not require an external energy source, the researchers said.

Ozden said the production of carbon nanotube arrays at a scale necessary to put the invention to practical use remains a bottleneck. “If it becomes possible to make large-scale nanotube forests, it will be a very easy material to make,” he said.

This is not the first time researchers have used the Stenocara beetle (also known as the Namib desert beetle) as inspiration for a water-harvesting material. In a Nov. 26, 2012 posting I traced the inspiration  back to 2001 while featuring the announcement of a new startup company,

… US startup company, NBD Nano, which aims to bring a self-filling water bottle based on Namib desert beetle to market,

NBD Nano, which consists of four recent university graduates and was formed in May [2012], looked at the Namib Desert beetle that lives in a region that gets about half an inch of rainfall per year.

Using a similar approach, the firm wants to cover the surface of a bottle with hydrophilic (water-attracting) and hydrophobic (water-repellent) materials.

The work is still in its early stages, but it is the latest example of researchers looking at nature to find inspiration for sustainable technology.

“It was important to apply [biomimicry] to our design and we have developed a proof of concept and [are] currently creating our first fully-functional prototype,” Miguel Galvez, a co-founder, told the BBC.

“We think our initial prototype will collect anywhere from half a litre of water to three litres per hour, depending on local environments.”

You can find out more about NBD Nano here although they don’t give many details about the material they’ve developed. Given that MIT (Massachusetts Institute of Technology) researchers published a  paper about a polymer-based material laced with silicon nanoparticles inspired by the Namib beetle in 2006 and that NBD Nano is based Massachusetts, I believe NBD Nano is attempting to commercialize the material or some variant developed at MIT.

Getting back to Rice University and carbon nanotubes, this is a different material attempting to achieve the same goal, harvesting water from desert air. Here’s a link to and a citation for the latest paper inspired by the Stenocara beetle (Namib beetle),

Anisotropically Functionalized Carbon Nanotube Array Based Hygroscopic Scaffolds by Sehmus Ozden, Liehui Ge , Tharangattu N. Narayanan , Amelia H. C. Hart , Hyunseung Yang , Srividya Sridhar , Robert Vajtai , and Pulickel M Ajayan. ACS Appl. Mater. Interfaces, DOI: 10.1021/am5022717 Publication Date (Web): June 4, 2014

Copyright © 2014 American Chemical Society

This paper is behind a paywall.

One final note, the research at MIT was funded by DARPA (US Defense Advanced Research Projects Agency). According to the news release the Rice University research held interest for similar agencies,

The U.S. Department of Defense and the U.S. Air Force Office of Scientific Research Multidisciplinary University Research Initiative supported the research.

Nanofiltration of heavy metals from water in Mexico

A June 3, 2013 news item on Nanowerk highlights a technology for filtering heavy metals from water,

The methods traditionally used to remove heavy metals from wastewater have limitations because they only withdraw a certain percentage and the remaining amount is very difficult to remove. This motivated a young graduate researcher at the National Polytechnic Institute (IPN) in Mexico, Gabriel Ramirez Monter, to create a technology capable of removing such contaminants at low cost and with an efficiency that surpasses existing technologies.

According to Monter Ramirez, this project led him to design some structures called dendrimers, which are highly branched molecules with shape similar to a shrub or a tree with multiple branches.

“Dendrimers adhere and spread on a microfiltration membrane; ie, thin sheets of porous material that are not normally capable of retaining heavy metals due to its pore size. Once placed, it achieves total removal of heavy metal ions in the same way a marine anemone would act, using tentacles to concentrate and catch food; in this case, the branches of the dendrimers capture pollutants, “says the researcher.

He explains that through dendrimers the team converted a microfiltration membrane into a nanofiltration one. “Another advantage of these structures is that they can be washed and reused, plus the captured metals are removed without problem.”

A May 27, 2014 Investigación y Desarrollo news release (Spanish language), which originated the news item, provides more details (or you can check Nanowerk for an English translation).

After some searching I found this 2012 YouTube presentation featuring researcher, Gabriel Ramirez Monter, discussing his work in Spanish,

According to the news item on Nanowerk, Ramirez Monter is in the early stages of commercializing his work. While the partner organization is identified as ‘Nanotecnología México’, I believe the correct name is Nano Tec México.

Water cages made of buckyballs could affect nuclear magnetic resonance and magnetic resonance imaging (MRI)

I wasn’t expecting to find this May 20, 2014 news item on Nanowerk to be* quite so fascinating, especially as It gets off to a slow start (a link has been removed),

In a new paper in The Journal of Chemical Physics (“Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance”), produced by AIP Publishing, a research team in the United Kingdom and the United States describes how water molecules “caged” in fullerene spheres (“buckyballs”) are providing a deeper insight into spin isomers — varieties of a molecule that differ in their nuclear spin. The results of this work may one day help enhance the analytical and diagnostic power of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI).

A May 20, 2014 American Institute of Physics (AIP) news release on EurekAlert, which originated the news item, provides some information about water molecules prior to describing the research in more detail,

Water molecules can exist as one of two isomers depending on how the spins of their two hydrogen atoms are oriented: ortho, where the spins are parallel and have a spin number of 1, and para, where the spins are antiparallel and have a spin number of 0. Scientists believe that any given molecule can transform from ortho- into para- spin states and vice versa, a process known as nuclear spin conversion.

“Currently, mechanisms for this conversion are not completely understood, nor how long it takes the molecules to transform from one spin isomer to the other,” said Salvatore Mamone, a post-doctoral physicist at the University of Southampton and lead author on the JCP paper. “To study this, we had to figure out how to reduce the strong intermolecular interactions that are responsible for aggregation and lower the rotational mobility of the water molecules.”

Next, there’s a brief summarized version of the research (from the news release),

The answer was to use chemical reactions to open a hole in fullerene (C60, also known as a buckyball) spheres, inject water molecules and then close the “cages” to form a complex referred to as H2O@C60. “At the end of this synthetic preparation nicknamed ‘molecular surgery,’ we find that 70 to 90 percent of the cages are filled, giving us a significant quantity of water molecules to examine,” Mamone said. “Because the [water] molecules are kept separated by the cages, there is a large rotational freedom that makes observation of the ortho and para isomers possible.”

This is followed by more technical details,

In their experiment, the researchers quickly cooled the individual H2O@C60 samples from 50 Kelvin (minus 223 degrees Celsius) to 5 K (minus 268 degrees Celsius) and then monitored their NMR signal every few minutes over several days.

“As the observed NMR signal is proportional to the amount of ortho-water in the sample [para-water with its spin number of 0 is "NMR silent"], we can track the percentages of ortho and para isomers at any time and any temperature,” Mamone explained. “At 50 K, we find that 75 percent of the water molecules are ortho, while at 5 K, they become almost 100 percent para. Therefore, we know that after the quick temperature jump, equilibrium is restored by conversion from ortho to para—and we see that conversion in real time.”

A surprising outcome of the experiment was that the researchers observed a second-order rate law in the kinetics of the spin conversion which proves that pairs of molecules have to interact for conversion to occur. “Previous studies have speculated that other nuclear spins can cause conversion but we found this not to be the case for H2O@C60,” Mamone said.

Next up, the research team plans to study the roles of isomer concentrations and temperature in the conversion process, the conversion of para-water to ortho (“back conversion”), how to detect single ortho- and para-water molecules on surfaces, and spin isomers in other fullerene-caged molecules.

Bravo to the news release writer for a very nice explanation of the science!

Here’s a link to and a citation for the paper,

Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance by Salvatore Mamone, Maria Concistré, Elisa Carignani, Benno Meier, Andrea Krachmalnicoff, Ole G. Johannessen, Xuegong Lei, Yongjun Li, Mark Denning, Marina Carravetta, Kelvin Goh, Anthony J. Horsewill, Richard J. Whitby and Malcolm H. Levitt.  J. Chem. Phys. 140, 194306 (2014) DOI: 10.1063/1.4873343

This is an open access paper.

* ‘to be’ added on July 16, 2014.

Research into the properties of water at the nanoscale and water droplet networks

I have two pieces of research with the only common element being water. First, there’s a May 9, 2014 news release on EurekAlert issued by the Politecnico di Torino (Italy; rough translation: Turin Polytechnic),

Swimming in a honey pool. That’s the sensation a water molecule should “feel” while approaching a solid surface within a nanometer (i.e. less than a ten-thousandth of hair diameter). The reduction in water mobility in the very close proximity of surfaces at the nanoscale is the well-known phenomenon of “nanoconfinement”, and it is due to both electrostatic and van der Waals attractive forces ruling matter interactions at that scale.

In this context, scientists from Politecnico di Torino and Houston Methodist Research Institute have taken a further step forward, by formulating a quantitative model and a physical interpretation able of predicting the nanoconfinement effect in a rather general framework. In particular, geometric and chemical characteristics as well as physical conditions of diverse nanoconfining surfaces (e.g. proteins, carbon nanotubes, silica nanopores or iron oxide nanoparticles) have been quantitatively related to mobility reduction and “supercooling” conditions of water, namely the persistence of water in a liquid state at temperatures far below 0°C, when close to a solid surface.

This result has been achieved after two years of in silico (i.e. computer-based) and in vitro (i.e. experiment-driven) activities by Eliodoro Chiavazzo, Matteo Fasano, Pietro Asinari (Multi-Scale Modelling Lab, Department of Energy at Politecnico di Torino) and Paolo Decuzzi (Center for the Rational Design of Multifunctional Nanoconstructs at Houston Methodist Research Institute).

I love the image of swimming in a ‘honey pool’ and while developing a schema for predicting a nanoconfinement effect may not seem all that exciting to an outsider the applications are varied according to the news release,

This study may soon find applications in the optimization and rational design of a broad variety of novel technologies ranging from applied physics (e.g. “nanofluids”, suspensions made out of water and nanoparticles for enhancing heat transfer) to sustainable energy (e.g. thermal storage based on nanoconfined water within sorbent materials); from detection and removal of pollutant from water (e.g. molecular sieves) to nanomedicine.

In fact this work is finding an immediate application in the field of medicine as pertaining to magnetic resonance imaging (MRI), from the news release,

The latter is the field where the research has indeed found a first important application. Every year, almost sixty millions of Magnetic Resonance Imaging (MRI) scans are performed, with diagnostic purposes. In the past decade, MRI technology benefitted from various significant scientific advances, which allowed more precise and sharper images of pathological tissues. Among other, contrast agents (i.e. substances used for improving contrast of structures or fluids within the body) importantly contributed in enhancing MRI performances.

This research activity has been able to explain and predict the increase in MRI performances due to nanoconfined contrast agents, which are currently under development at the Houston Methodist Research Institute. Hence, the discovery paves the way to further increase in the quality of MRI images, in order to possibly improve chances of earlier and more accurate detection of diseases in millions of patients, every year.

Here’s a link to and a citation for the research paper,

Scaling behaviour for the water transport in nanoconfined geometries by Eliodoro Chiavazzo, Matteo Fasano, Pietro Asinari & Paolo Decuzzi. Nature Communications 5 Article number: 4565 doi:10.1038/ncomms4565 Published 03 April 2014

This is an open access paper and, unusually, I am excerpting the Abstract as I find it helps to further explain this work (although the more technical aspects are lost on me),

The transport of water in nanoconfined geometries is different from bulk phase and has tremendous implications in nanotechnology and biotechnology. Here molecular dynamics is used to compute the self-diffusion coefficient D of water within nanopores, around nanoparticles, carbon nanotubes and proteins. For almost 60 different cases, D is found to scale linearly with the sole parameter θ as D(θ)=DB[1+(DC/DB−1)θ], with DB and DC the bulk and totally confined diffusion of water, respectively. The parameter θ is primarily influenced by geometry and represents the ratio between the confined and total water volumes. The D(θ) relationship is interpreted within the thermodynamics of supercooled water. As an example, such relationship is shown to accurately predict the relaxometric response of contrast agents for magnetic resonance imaging. The D(θ) relationship can help in interpreting the transport of water molecules under nanoconfined conditions and tailoring nanostructures with precise modulation of water mobility.

The second piece of ‘water’ research was featured in a May 13, 2014 news item on Nanowerk,

A simple new technique to form interlocking beads of water in ambient conditions could prove valuable for applications in biological sensing, membrane research and harvesting water from fog.

Researchers at the Department of Energy’s Oak Ridge National Laboratory have developed a method to create air-stable water droplet networks known as droplet interface bilayers. These interconnected water droplets have many roles in biological research because their interfaces simulate cell membranes. Cumbersome fabrication methods, however, have limited their use.

A May 13, 2014 Oak Ridge National Laboratory (ORNL) news release, which originated the news item, provides more details,

“The way they’ve been made since their inception is that two water droplets are formed in an oil bath then brought together while they’re submerged in oil,” said ORNL’s Pat Collier, who led the team’s study published in the Proceedings of the National Academy of Sciences. “Otherwise they would just pop like soap bubbles.”

Instead of injecting water droplets into an oil bath, the ORNL research team experimented with placing the droplets on a superhydrophobic surface infused with a coating of oil. The droplets aligned side by side without merging.

To the researchers’ surprise, they were also able to form non-coalescing water droplet networks without including lipids in the water solution. Scientists typically incorporate phospholipids into the water mixture, which leads to the formation of an interlocking lipid bilayer between the water droplets.

“When you have those lipids at the interfaces of the water drops, it’s well known that they won’t coalesce because the interfaces join together and form a stable bilayer,” ORNL coauthor Jonathan Boreyko said. “So our surprise was that even without lipids in the system, the pure water droplets on an oil-infused surface in air still don’t coalesce together.”

The team’s research revealed how the unexpected effect is caused by a thin oil film that is squeezed between the pure water droplets as they come together, preventing the droplets from merging into one. Watch a video of the process on ORNL’s YouTube channel.

With or without the addition of lipids, the team’s technique offers new insight for a host of applications. Controlling the behavior of pure water droplets on oil-infused surfaces is key to developing dew- or fog-harvesting technology as well as more efficient condensers, for instance.

“Our finding of this non-coalescence phenomenon will shed light on these droplet-droplet interactions that can occur on oil-infused systems,” Boreyko said.

The ability to create membrane-like water droplet networks by adding lipids leads to a different set of functional applications, Collier noted.

“These bilayers can be used in anything from synthetic biology to creating circuits to bio-sensing applications,” he said. “For example, we could make a bio-battery or a signaling network by stringing some of these droplets together. Or, we could use it to sense the presence of airborne molecules.”

The team’s study also demonstrated ways to control the performance and lifetime of the water droplets by manipulating oil viscosity and temperature and humidity levels.

Here’s another link to the paper and a citation,

Air-stable droplet interface bilayers on oil-infused surfaces by Jonathan B. Boreyko, Georgios Polizos, Panos G. Datskos, Stephen A. Sarles, and C. Patrick Collier.  PNAS 2014 ; published ahead of print May 12, 2014, doi: 10.1073/pnas.1400381111

This paper is behind a paywall.

Environmental impacts and graphene

Researchers at the University of California at Riverside (UCR) have published the results of what they claim is the first study featuring the environmental impact from graphene use. From the April 29, 2014 news item on ScienceDaily,

In a first-of-its-kind study of how a material some think could transform the electronics industry moves in water, researchers at the University of California, Riverside Bourns College of Engineering found graphene oxide nanoparticles are very mobile in lakes or streams and therefore may well cause negative environmental impacts if released.

Graphene oxide nanoparticles are an oxidized form of graphene, a single layer of carbon atoms prized for its strength, conductivity and flexibility. Applications for graphene include everything from cell phones and tablet computers to biomedical devices and solar panels.

The use of graphene and other carbon-based nanomaterials, such as carbon nanotubes, are growing rapidly. At the same time, recent studies have suggested graphene oxide may be toxic to humans. [emphasis mine]

As production of these nanomaterials increase, it is important for regulators, such as the Environmental Protection Agency, to understand their potential environmental impacts, said Jacob D. Lanphere, a UC Riverside graduate student who co-authored a just-published paper about graphene oxide nanoparticles transport in ground and surface water environments.

I wish they had cited the studies suggesting graphene oxide (GO) may be toxic. After a quick search I found: Internalization and cytotoxicity of graphene oxide and carboxyl graphene nanoplatelets in the human hepatocellular carcinoma cell line Hep G2 by Tobias Lammel, Paul Boisseaux, Maria-Luisa Fernández-Cruz, and José M Navas (free access paper in Particle and Fibre Toxicology 2013, 10:27 http://www.particleandfibretoxicology.com/content/10/1/27). From what I can tell, this was a highly specialized investigation conducted in a laboratory. While the results seem concerning it’s difficult to draw conclusions from this study or others that may have been conducted.

Dexter Johnson in a May 1, 2014 post on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website) provides more relevant citations and some answers (Note: Links have been removed),

While the UC Riverside  did not look at the toxicity of GO in their study, researchers at the Hersam group from Northwestern University did report in a paper published in the journal Nano Letters (“Minimizing Oxidation and Stable Nanoscale Dispersion Improves the Biocompatibility of Graphene in the Lung”) that GO was the most toxic form of graphene-based materials that were tested in mice lungs. In other research published in the Journal of Hazardous Materials (“Investigation of acute effects of graphene oxide on wastewater microbial community: A case study”), investigators determined that the toxicity of GO was dose dependent and was toxic in the range of 50 to 300 mg/L. So, below 50 mg/L there appear to be no toxic effects to GO. To give you some context, arsenic is considered toxic at 0.01 mg/L.

Dexter also contrasts graphene oxide with graphene (from his May 1, 2014 post; Note: A link has been removed),

While GO is quite different from graphene in terms of its properties (GO is an insulator while graphene is a conductor), there are many applications that are similar for both GO and graphene. This is the result of GO’s functional groups allowing for different derivatives to be made on the surface of GO, which in turn allows for additional chemical modification. Some have suggested that GO would make a great material to be deposited on additional substrates for thin conductive films where the surface could be tuned for use in optical data storage, sensors, or even biomedical applications.

Getting back to the UCR research, an April 28, 2014 UCR news release (also on EurekAlert but dated April 29, 2014) describes it  in more detail,

Walker’s [Sharon L. Walker, an associate professor and the John Babbage Chair in Environmental Engineering at UC Riverside] lab is one of only a few in the country studying the environmental impact of graphene oxide. The research that led to the Environmental Engineering Science paper focused on understanding graphene oxide nanoparticles’ stability, or how well they hold together, and movement in groundwater versus surface water.

The researchers found significant differences.

In groundwater, which typically has a higher degree of hardness and a lower concentration of natural organic matter, the graphene oxide nanoparticles tended to become less stable and eventually settle out or be removed in subsurface environments.

In surface waters, where there is more organic material and less hardness, the nanoparticles remained stable and moved farther, especially in the subsurface layers of the water bodies.

The researchers also found that graphene oxide nanoparticles, despite being nearly flat, as opposed to spherical, like many other engineered nanoparticles, follow the same theories of stability and transport.

I don’t know what conclusions to draw from the information that the graphene nanoparticles remain stable and moved further in the water. Is a potential buildup of graphene nanoparticles considered a problem because it could end up in our water supply and we would be poisoned by these particles? Dexter provides an answer (from his May 1, 2014 post),

Ultimately, the question of danger of any material or chemical comes down to the simple equation: Hazard x Exposure=Risk. To determine what the real risk is of GO reaching concentrations equal to those that have been found to be toxic (50-300 mg/L) is the key question.

The results of this latest study don’t really answer that question, but only offer a tool by which to measure the level of exposure to groundwater if there was a sudden spill of GO at a manufacturing facility.

While I was focused on ingestion by humans, it seems this research was more focused on the natural environment and possible future poisoning by graphene oxide.

Here’s a link to and a citation for the paper,

Stability and Transport of Graphene Oxide Nanoparticles in Groundwater and Surface Water by Jacob D. Lanphere, Brandon Rogers, Corey Luth, Carl H. Bolster, and Sharon L. Walker. Environmental Engineering Science. -Not available-, ahead of print. doi:10.1089/ees.2013.0392.

Online Ahead of Print: March 17, 2014

If available online, this is behind a paywall.