Tag Archives: water

Soap and water for creating 2D nanoflakes (hexagonal boron nitride [hBN] sheets)

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Rice University (Texas, US) has a pretty image illustrating the process of making 2D nanoflakes,

Caption: The image displays the exfoliation of hexagonal boron nitride into atomically thin nanosheets aided by surfactants, a process refined by chemists at Rice University. Credit: Ella Maru Studio

A January 27, 2021 news item on Nanowerk announces the Rice University news,

Just a little soap helps clean up the challenging process of preparing two-dimensional hexagonal boron nitride (hBN).

Rice University chemists have found a way to get the maximum amount [number] of quality 2D hBN nanosheets from its natural bulk form by processing it with surfactant (aka soap) and water. The surfactant surrounds and stabilizes the microscopic flakes, preserving their properties.

Experiments by the lab of Rice chemist Angel Martí identified the “sweet spot” for making stable dispersions of hBN, which can be processed into very thin antibacterial films that handle temperatures up to 900 degrees Celsius (1,652 degrees Fahrenheit).

…

A brief grammatical moment: I can see where someone might view it as arguable (see second paragraph of the above excerpt) but for me ‘amount’ is for something like ‘flour’ for an ‘amount of flour’. ‘Number’ is for something like a ‘number of sheets’. The difference lies in your ability to count the items. Generally speaking, you can’t count the number of flour, therefore, it’s the amount of flour, but you can count the number of sheets. Can count these hexagonal boron nitride (hBN) sheets? If not, is what makes this arguable.

A January 27, 2021 Rice University news release (also on EurekAlert), which originated the news item, delves into details,

The work led by Martí, alumna Ashleigh Smith McWilliams and graduate student Cecilia Martínez-Jiménez is detailed in the American Chemical Society journal ACS Applied Nano Materials.

“Boron nitride materials are interesting, particularly because they are extremely resistant to heat,” Martí said. “They are as light as graphene and carbon nanotubes, but you can put hBN in a flame and nothing happens to it.”

He said bulk hBN is cheap and easy to obtain, but processing it into microscopic building blocks has been a challenge. “The first step is to be able to exfoliate and disperse them, but research on how to do that has been scattered,” Martí said. “When we decided to set a benchmark, we found the processes that have been extremely useful for graphene and nanotubes don’t work as well for boron nitride.”

Sonicating bulk hBN in water successfully exfoliated the material and made it soluble. “That surprised us, because nanotubes or graphene just float on top,” Martí said. “The hBN dispersed throughout, though they weren’t particularly stable.

“It turned out the borders of boron nitride crystals are made of amine and nitric oxide groups and boric acid, and all of these groups are polar (with positive or negative charge),” he said. “So when you exfoliate them, the edges are full of these functional groups that really like water. That never happens with graphene.”

Experiments with nine surfactants helped them find just the right type and amount to keep 2D hBN from clumping without cutting individual flakes too much during sonication. The researchers used 1% by weight of each surfactant in water, added 20 milligrams of bulk hBN, then stirred and sonicated the mix.

Spinning the resulting solutions at low and high rates showed the greatest yield came with the surfactant known as PF88 under 100-gravity centrifugation, but the highest-quality nanosheets came from all the ionic surfactants under 8,000 g centrifugation, with the greatest stability from common ionic surfactants SDS and CTAC.

DTAB — short for dodecyltrimethylammonium bromide — under high centrifugation proved best at balancing the yield and quality of 2D hBN. The researchers also produced a transparent film from hBN nanosheets dispersed in SDS and water to demonstrate how they can be processed into useful products.

“We describe the steps you need to do to produce high-quality hBN flakes,” Martí said. “All of the steps are important, and we were able to bring to light the consequences of each one.”

Understanding the Exfoliation and Dispersion of Hexagonal Boron Nitride Nanosheets by Surfactants: Implications for Antibacterial and Thermally Resistant Coatings by Ashleigh D. Smith McWilliams, Cecilia Martínez-Jiménez, Asia Matatyaho Ya’akobi, Cedric J. Ginestra, Yeshayahu Talmon, Matteo Pasquali, and Angel A. Martí. ACS Appl. Nano Mater. 2021, 4, 1, 142–151 DOI: https://doi.org/10.1021/acsanm.0c02437 Publication Date: January 7, 2021 Copyright © 2021 American Chemical Society

This paper is behind a paywall.

Chinese scientists strike gold in plant tissues

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I have heard of phytomining in soil remediation efforts (reclaiming nanoscale metals in plants near mining operations; you can find a more detailed definition here at Wiktionary) but, in this case, scientists have discovered plant tissues with nanoscale gold in an area which has no known deposits of gold. From a June 14, 2018 news item on Nanowwerk (Note: A link has been removed),

Plants containing the element gold are already widely known. The flowering perennial plant alfafa, for example, has been cultivated by scientists to contain pure gold in its plant tissue. Now researchers from the Sun Yat-sen University in China have identified and investigated the characteristics of gold nanoparticles in two plant species growing in their natural environments.

The study, led by Xiaoen Luo, is published in Environmental Chemistry Letters (“Discovery of nano-sized gold particles in natural plant tissues”) and has implications for the way gold nanoparticles are produced and absorbed from the environment.

A June 14, 2018 Springer Publications press release, which originated the news item, delves further and proposes a solution to the mystery,

Xiaoen Luo and her colleagues investigated the perennial shrub B. nivea and the annual or biennial weed Erigeron Canadensis. The researchers collected and prepared samples of both plants so that they could be examined using the specialist analytical tool called field-emission transmission electron microscope (TEM).

Gold-bearing nanoparticles – tiny gold particles fused with another element such as oxygen or copper – were found in both types of plant. In E. Canadensis these particles were around 20-50 nm in diameter and had an irregular form. The gold-bearing particles in B. nivea were circular, elliptical or bone-rod shaped with smooth edges and were 5-15 nm.

“The abundance of gold in the crust is very low and there was no metal deposit in the sampling area so we speculate that the source of these gold nanoparticles is a nearby electroplating plant that uses gold in its operations, “ explains Jianjin Cao who is a co-author of the study.

Most of the characteristics of the nanoparticles matched those of artificial particles rather than naturally occurring nanoparticles, which would support this theory. The researchers believe that the gold-bearing particles were absorbed through the pores of the plants directly, indicating that gold could be accumulated from the soil, water or air.

“Discovering gold-bearing nanoparticles in natural plant tissues is of great significance and allows new possibilities to clean up areas contaminated with nanoparticles, and also to enrich gold nanoparticles using plants,” says Xiaoen Luo.

The researchers plan to further study the migration mechanism, storage locations and growth patterns of gold nanoparticles in plants and also verify the absorbing capacity of different plants for gold nanoparticles in polluted areas.

For anyone who’d like to find out more about electroplating, there’s this January 25, 2018 article by Anne Marie Helmenstine for ThoughtCo.

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

Discovery of nano-sized gold particles in natural plant tissues by Xiaoen Luo (Luo, X.) and Jianjin Cao (Cao, J.). Environ Chem Lett (2018) pp 1–8 https://doi.org/10.1007/s10311-018-0749-0 First published online 14 June 2018

This paper appears to be open access.

Spider glue

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Caption: An orb spider, glue-maker extraordinaire, at work on a web. Credit: The University of Akron

Scientists are taking inspiration from spiders in their quest to develop better adhesives. (Are they abandoning the gecko? Usually when scientists study adhesiveness, there’s talk of geckos. From a June 5, 2018 news item on ScienceDaily,

Ever wonder why paint peels off the wall during summer’s high humidity? It’s the same reason that bandages separate from skin when we bathe or swim.

Interfacial water, as it’s known, forms a slippery and non-adhesive layer between the glue and the surface to which it is meant to stick, interfering with the formation of adhesive bonds between the two.

Overcoming the effects of interfacial water is one of the challenges facing developers of commercial adhesives.

To find a solution, researchers at The University of Akron (UA) are looking to one of the strongest materials found in nature: spider silk.

The sticky glue that coats the silk threads of spider webs is a hydrogel, meaning it is full of water. One would think, then, that spiders would have difficulty catching prey, especially in humid conditions — but they do not. In fact, their sticky glue, which has been a subject of intensive research for years, is one of the most effective biological glues in all of nature.

A June 4, 2018 University of Akron news release (also on EurekAlert published on June 5, 2018), which originated the news item, provides more detail,

So how is spider glue able to stick in highly humid conditions?

That question was the subject of investigation by UA graduate students Saranshu Singla, Gaurav Amarpuri and Nishad Dhopatkar, who have been working with Dr. Ali Dhinojwala, interim dean of the College of Polymer Science and Polymer Engineering, and Dr. Todd Blackledge, professor of biology in the Integrated Bioscience program. Both professors are principal investigators in UA’s Biomimicry Research Innovation Center [BRIC], which specializes in emulating biological forms, processes, patterns and systems to solve technical challenges.

The team’s findings, which may provide the clue to developing stronger commercial adhesives, can be read in a paper recently published in the journal Nature Communications.

Singla and her colleagues set out to examine the secret behind the success of the common orb spider (Larinioides cornutus) glue and uncover how it overcomes the primary obstacle of achieving good adhesion in the humid conditions where water could be present between the glue and the target surface.

To investigate the processes involved, the team took orb spider glue, set it on sapphire substrate, then examined it using a combination of interface-sensitive spectroscopy and infrared spectroscopy.

Spider glue is made of three elements: two specialized glycoproteins, a collection of low molecular mass organic and inorganic compounds (LMMCs), and water. The LMMCs are hygroscopic (water-attracting), which keeps the glue soft and tacky to stick.

Singla and her team discovered that these glycoproteins act as primary binding agents to the surface. Glycoprotein-based glues have been identified in several other biological glues, such as fungi, algae, diatoms, sea stars, sticklebacks and English ivy.

But why doesn’t the water present in the spider glue interfere with the adhesive contact the way it does with most synthetic adhesives?

The LMMCs, the team concluded, perform a previously unknown function of sequestering interfacial water, preventing adhesive failure.

Singla and colleagues determined that it is the interaction of glycoproteins and LMMCs that governs the adhesive quality of the glue produced, with the respective proportions varying across species, thus optimizing adhesive strength to match the relative humidity of spider habitat.

“The hygroscopic compounds – known as water-absorbers – in spider glue play a previously unknown role in moving water away from the boundary, thereby preventing failure of spider glue at high humidity,” explained Singla.

The ability of the spider glue to overcome the problem of interfacial water by effectively absorbing it is the key finding of the research, and the one with perhaps the strongest prospect for commercial development.

“Imagine a paint that is guaranteed for life, come rain or shine,” Singla remarked.

All thanks to your friendly neighborhood spider glue.

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

Hygroscopic compounds in spider aggregate glue remove interfacial water to maintain adhesion in humid conditions by Saranshu Singla, Gaurav Amarpuri, Nishad Dhopatkar, Todd A. Blackledge, & Ali Dhinojwala. Nature Communicationsvolume 9, Article number: 1890 (2018) Published 22 May 2018 DOI: https://doi.org/10.1038/s41467-018-04263-z

This paper is open access.

Removing more than 99% of crude oil from ‘produced’ water (well water)

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Should you have an oil well nearby (see The Urban Oil Fields of Los Angeles in an August 28, 2014 photo essay by Alan Taylor for The Atlantic for examples of oil wells in various municipalities and cities associated with LS) , this news from Texas may interest you.

From an August 15, 2018 news item on Nanowerk,

Oil and water tend to separate, but they mix well enough to form stable oil-in-water emulsions in produced water from oil reservoirs to become a problem. Rice University scientists have developed a nanoparticle-based solution that reliably removes more than 99 percent of the emulsified oil that remains after other processing is done.
The Rice lab of chemical engineer Sibani Lisa Biswal made a magnetic nanoparticle compound that efficiently separates crude oil droplets from produced water that have proven difficult to remove with current methods.

An August 15, 2018 Rice University news release (also on EurekAlert), which originated the news item, describes the work in more detail,

Produced water [emphasis mine] comes from production wells along with oil. It often includes chemicals and surfactants pumped into a reservoir to push oil to the surface from tiny pores or cracks, either natural or fractured, deep underground. Under pressure and the presence of soapy surfactants, some of the oil and water form stable emulsions that cling together all the way back to the surface.

While methods exist to separate most of the oil from the production flow, engineers at Shell Global Solutions, which sponsored the project, told Biswal and her team that the last 5 percent of oil tends to remain stubbornly emulsified with little chance to be recovered.

“Injected chemicals and natural surfactants in crude oil can oftentimes chemically stabilize the oil-water interface, leading to small droplets of oil in water which are challenging to break up,” said Biswal, an associate professor of chemical and biomolecular engineering and of materials science and nanoengineering.

The Rice lab’s experience with magnetic particles and expertise in amines, courtesy of former postdoctoral researcher and lead author Qing Wang, led it to combine techniques. The researchers added amines to magnetic iron nanoparticles. Amines carry a positive charge that helps the nanoparticles find negatively charged oil droplets. Once they do, the nanoparticles bind the oil. Magnets are then able to pull the droplets and nanoparticles out of the solution.

“It’s often hard to design nanoparticles that don’t simply aggregate in the high salinities that are typically found in reservoir fluids, but these are quite stable in the produced water,” Biswal said.

The enhanced nanoparticles were tested on emulsions made in the lab with model oil as well as crude oil.

In both cases, researchers inserted nanoparticles into the emulsions, which they simply shook by hand and machine to break the oil-water bonds and create oil-nanoparticle bonds within minutes. Some of the oil floated to the top, while placing the test tube on a magnet pulled the infused nanotubes to the bottom, leaving clear water in between.

Best of all, Biswal said, the nanoparticles can be washed with a solvent and reused while the oil can be recovered. The researchers detailed six successful charge-discharge cycles of their compound and suspect it will remain effective for many more.

She said her lab is designing a flow-through reactor to process produced water in bulk and automatically recycle the nanoparticles. That would be valuable for industry and for sites like offshore oil rigs, where treated water could be returned to the ocean.

It seems to me that ‘produced water’ is another term for polluted water.I guess it’s the reverse to Shakespeare’s “a rose by any other name would smell as sweet” with polluted water by any other name seeming more palatable.

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

Recyclable amine-functionalized magnetic nanoparticles for efficient demulsification of crude oil-in-water emulsions by Qing Wang, Maura C. Puerto, Sumedh Warudkar, Jack Buehler, and Sibani L. Biswal. Environ. Sci.: Water Res. Technol., 2018, Advance Article DOI: 10.1039/C8EW00188J First published on 15 Aug 2018

This paper is behind a paywall.

Rice has included this image amongst others in their news release,

Rice University engineers have developed magnetic nanoparticles that separate the last droplets of oil from produced water at wells. The particles draw in the bulk of the oil and are then attracted to the magnet, as demonstrated here. Photo by Jeff Fitlow

There’s also this video, which, in my book, borders on magical,

Organic nanoelectronics in water

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Researchers in Sweden have developed organic electronics that are stable in water according to a January 11, 2018 news item on ScienceDaily,

Researchers at the Laboratory of Organic Electronics, Linköping University [Sweden], have developed the world’s first complementary electrochemical logic circuits that can function stably for long periods in water. This is a highly significant breakthrough in the development of bioelectronics.

A January 11, 2018 Linköping University press release, which originated the news item, notes this latest advance is based on work that started in 2002,

Complementary logic circuitComplementary logic circuit Photo credit: Thor Balkhed

The first printable organic electrochemical transistors were presented by researchers at LiU as early as 2002, and research since then has progressed rapidly. Several organic electronic components, such as light-emitting diodes and electrochromic displays, are already commercially available.

The dominating material used until now has been PEDOT:PSS, which is a p-type material, in which the charge carriers are holes. In order to construct effective electron components, a complementary material, n-type, is required, in which the charge carriers are electrons.
It has been difficult to find a sufficiently stable polymer material, one that can operate in water media and in which the long polymer chains can sustain high current when the material is doped.

N-type material

In an article in the prestigious scientific journal Advanced Materials, Simone Fabiano, head of research in the Organic Nanoelectronics group at the Laboratory of Organic Electronics, presents, together with his colleagues, results from an n-type conducting material in which the ladder-type structure of the polymer backbone favours ambient stability and high current when doped. One example is BBL, poly(benzimidazobenzophenanthroline), a material often used in solar cell research.

Postdoctoral researcher Hengda Sun has found a method to create thick films of the material. The thicker the film, the greater the conductivity.

“We have used spray-coating to produce films up to 200 nm thick. These can reach extremely high conductivities,” says Simone Fabiano.

The method can also be successfully used together with printed electronics across large surfaces.

Hengda Sun has also shown that the circuits function for long periods, both in the presence of oxygen and water.

Moist surroundings

“This may appear at first glance to be a small advance in a specialised field, but what is great about it is that it has major consequences for many applications. We can now construct complementary logic circuits – inverters, sensors and other components – that function in moist surroundings,” says Simone Fabiano.

“Resistors are needed in logical circuits that are based solely on p-type electrochemical transistors. These are rather bulky, and this limits the applications that can be achieved. With an n-type material in our toolbox, we can produce complementary circuits that occupy the available space much more efficiently, since resistors are no longer required in the logical circuits,” says Magnus Berggren, professor of organic electronics and head of the Laboratory for Organic Electronics.

Applications of the organic components include logic circuits that can be printed on textile or paper, various types of cheap sensor, non-rigid and flexible displays, and – not least – the huge field of bioelectronics. Polymers that conduct both ions and electrons are the bridge needed between the ion-conducting systems in the body and the electronic components of, for example, sensors.

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

Complementary Logic Circuits Based on High-Performance n-Type Organic Electrochemical Transistors by Hengda Sun, Mikhail Vagin, Suhao Wang, Xavier Crispin, Robert Forchheimer, Magnus Berggren, and Simone Fabiano. Advanced Materials Vol. 30 Issue 3 Version of Record online: 10 JAN 2018 DOI: 10.1002/adma.201704916

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Cleaning up disasters with Hokusai’s blue and cellulose nanofibers to clean up contaminated soil and water in Fukushima

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The Great Wave off Kanagawa (Under a wave off Kanagawa”), also known as The Great Wave or simply The Wave, by Katsushika Hokusai – Metropolitan Museum of Art, online database: entry 45434, Public Domain, https://commons.wikimedia.org/w/index.php?curid=2798407

I thought it might be a good idea to embed a copy of Hokusai’s Great Wave and the blue these scientists in Japan have used as their inspiration. (By the way, it seems these scientists collaborated with Mildred Dresselhaus who died at the age of 86, a few months after their paper was published. In honour of he and before the latest, here’s my Feb. 23, 2017 posting about the ‘Queen of Carbon’.)

Now onto more current news, from an Oct. 13, 2017 news item on Nanowerk (Note: A link has been removed),

By combining the same Prussian blue pigment used in the works of popular Edo-period artist Hokusai and cellulose nanofiber, a raw material of paper, a University of Tokyo research team succeeded in synthesizing compound nanoparticles, comprising organic and inorganic substances (Scientific Reports, “Cellulose nanofiber backboned Prussian blue nanoparticles as powerful adsorbents for the selective elimination of radioactive cesium”). This new class of organic/inorganic composite nanoparticles is able to selectively adsorb, or collect on the surface, radioactive cesium.

The team subsequently developed sponges from these nanoparticles that proved highly effective in decontaminating the water and soil in Fukushima Prefecture exposed to radioactivity following the nuclear accident there in March 2011.

I think these are the actual sponges not an artist’s impression,

Decontamination sponge spawned from current study
Cellulose nanofiber-Prussian blue compounds are permanently anchored in spongiform chambers (cells) in this decontamination sponge. It can thus be used as a powerful adsorbent for selectively eliminating radioactive cesium. © 2017 Sakata & Mori Laboratory.

An Oct. 13, 2017 University of Tokyo press release, which originated the news item, provides more detail about the sponges and the difficulties of remediating radioactive air and soil,

Removing radioactive materials such as cesium-134 and -137 from contaminated seawater or soil is not an easy job. First of all, a huge amount of similar substances with competing functions has to be removed from the area, an extremely difficult task. Prussian blue (ferric hexacyanoferrate) has a jungle gym-like colloidal structure, and the size of its single cubic orifice, or opening, is a near-perfect match to the size of cesium ions; therefore, it is prescribed as medication for patients exposed to radiation for selectively adsorbing cesium. However, as Prussian blue is highly attracted to water, recovering it becomes highly difficult once it is dissolved into the environment; for this reason, its use in the field for decontamination has been limited.

Taking a hint from the Prussian blue in Hokusai’s woodblock prints not losing their color even when getting wet from rain, the team led by Professor Ichiro Sakata and Project Professor Bunshi Fugetsu at the University of Tokyo’s Nanotechnology Innovation Research Unit at the Policy Alternatives Research Institute, and Project Researcher Adavan Kiliyankil Vipin at the Graduate School of Engineering developed an insoluble nanoparticle obtained from combining cellulose and Prussian blue—Hokusai had in fact formed a chemical bond in his handling of Prussian blue and paper (cellulose).

The scientists created this cellulose-Prussian blue combined nanoparticle by first preparing cellulose nanofibers using a process called TEMPO oxidization and securing ferric ions (III) onto them, then introduced a certain amount of hexacyanoferrate, which adhered to Prussian blue nanoparticles with a diameter ranging from 5–10 nanometers. The nanoparticles obtained in this way were highly resistant to water, and moreover, were capable of adsorbing 139 mg of radioactive cesium ion per gram.

Field studies on soil decontamination in Fukushima have been underway since last year. A highly effective approach has been to sow and allow plant seeds to germinate inside the sponge made from the nanoparticles, then getting the plants’ roots to take up cesium ions from the soil to the sponge. Water can significantly shorten decontamination times compared to soil, which usually requires extracting cesium from it with a solvent.

It has been more than six years since the radioactive fallout from a series of accidents at the Fukushima Daiichi nuclear power plant following the giant earthquake and tsunami in northeastern Japan. Decontamination with the cellulose nanofiber-Prussian blue compound can lead to new solutions for contamination in disaster-stricken areas.

“I was pondering about how Prussian blue immediately gets dissolved in water when I happened upon a Hokusai woodblock print, and how the indigo color remained firmly set in the paper, without bleeding, even after all these years,” reflects Fugetsu. He continues, “That revelation provided a clue for a solution.”

“The amount of research on cesium decontamination increased after the Chernobyl nuclear power plant accident, but a lot of the studies were limited to being academic and insufficient for practical application in Fukushima,” says Vipin. He adds, “Our research offers practical applications and has high potential for decontamination on an industrial scale not only in Fukushima but also in other cesium-contaminated areas.”

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

Cellulose nanofiber backboned Prussian blue nanoparticles as powerful adsorbents for the selective elimination of radioactive cesium by Adavan Kiliyankil Vipin, Bunshi Fugetsu, Ichiro Sakata, Akira Isogai, Morinobu Endo, Mingda Li, & Mildred S. Dresselhaus. Scientific Reports 6, Article number: 37009 (2016) doi:10.1038/srep37009 Published online: 15 November 2016

This is open access.

Cyborg bacteria to reduce carbon dioxide

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This video is a bit technical but then it is about work being presented to chemists at the American Chemical Society’s (ACS) at the 254th National Meeting & Exposition Aug. 20 -24, 2017,

For a more plain language explanation, there’s an August 22, 2017 ACS news release (also on EurekAlert),

Photosynthesis provides energy for the vast majority of life on Earth. But chlorophyll, the green pigment that plants use to harvest sunlight, is relatively inefficient. To enable humans to capture more of the sun’s energy than natural photosynthesis can, scientists have taught bacteria to cover themselves in tiny, highly efficient solar panels to produce useful compounds.

…

“Rather than rely on inefficient chlorophyll to harvest sunlight, I’ve taught bacteria how to grow and cover their bodies with tiny semiconductor nanocrystals,” says Kelsey K. Sakimoto, Ph.D., who carried out the research in the lab of Peidong Yang, Ph.D. “These nanocrystals are much more efficient than chlorophyll and can be grown at a fraction of the cost of manufactured solar panels.”

Humans increasingly are looking to find alternatives to fossil fuels as sources of energy and feedstocks for chemical production. Many scientists have worked to create artificial photosynthetic systems to generate renewable energy and simple organic chemicals using sunlight. Progress has been made, but the systems are not efficient enough for commercial production of fuels and feedstocks.

Research in Yang’s lab at the University of California, Berkeley, where Sakimoto earned his Ph.D., focuses on harnessing inorganic semiconductors that can capture sunlight to organisms such as bacteria that can then use the energy to produce useful chemicals from carbon dioxide and water. “The thrust of research in my lab is to essentially ‘supercharge’ nonphotosynthetic bacteria by providing them energy in the form of electrons from inorganic semiconductors, like cadmium sulfide, that are efficient light absorbers,” Yang says. “We are now looking for more benign light absorbers than cadmium sulfide to provide bacteria with energy from light.”

Sakimoto worked with a naturally occurring, nonphotosynthetic bacterium, Moorella thermoacetica, which, as part of its normal respiration, produces acetic acid from carbon dioxide (CO2). Acetic acid is a versatile chemical that can be readily upgraded to a number of fuels, polymers, pharmaceuticals and commodity chemicals through complementary, genetically engineered bacteria.

When Sakimoto fed cadmium and the amino acid cysteine, which contains a sulfur atom, to the bacteria, they synthesized cadmium sulfide (CdS) nanoparticles, which function as solar panels on their surfaces. The hybrid organism, M. thermoacetica-CdS, produces acetic acid from CO2, water and light. “Once covered with these tiny solar panels, the bacteria can synthesize food, fuels and plastics, all using solar energy,” Sakimoto says. “These bacteria outperform natural photosynthesis.”

The bacteria operate at an efficiency of more than 80 percent, and the process is self-replicating and self-regenerating, making this a zero-waste technology. “Synthetic biology and the ability to expand the product scope of CO2 reduction will be crucial to poising this technology as a replacement, or one of many replacements, for the petrochemical industry,” Sakimoto says.

So, do the inorganic-biological hybrids have commercial potential? “I sure hope so!” he says. “Many current systems in artificial photosynthesis require solid electrodes, which is a huge cost. Our algal biofuels are much more attractive, as the whole CO2-to-chemical apparatus is self-contained and only requires a big vat out in the sun.” But he points out that the system still requires some tweaking to tune both the semiconductor and the bacteria. He also suggests that it is possible that the hybrid bacteria he created may have some naturally occurring analog. “A future direction, if this phenomenon exists in nature, would be to bioprospect for these organisms and put them to use,” he says.

For more insight into the work, check out Dexter Johnson’s Aug. 22, 2017 posting on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website),

“It’s actually a natural, overlooked feature of their biology,” explains Sakimoto in an e-mail interview with IEEE Spectrum. “This bacterium has a detoxification pathway, meaning if it encounters a toxic metal, like cadmium, it will try to precipitate it out, thereby detoxifying it. So when we introduce cadmium ions into the growth medium in which M. thermoacetica is hanging out, it will convert the amino acid cysteine into sulfide, which precipitates out cadmium as cadmium sulfide. The crystals then assemble and stick onto the bacterium through normal electrostatic interactions.”

I’ve just excerpted one bit, there’s more in Dexter’s posting.

Using a sponge to remove mercury from lake water

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I’ve heard of Lake Como in Italy but Como Lake in Minnesota is a new one for me. The Minnesota lake is featured in a March 22, 2017 news item about water and sponges on phys.org,

Mercury is very toxic and can cause long-term health damage, but removing it from water is challenging. To address this growing problem, University of Minnesota College of Food, Agricultural and Natural Sciences (CFANS) Professor Abdennour Abbas and his lab team created a sponge that can absorb mercury from a polluted water source within seconds. Thanks to the application of nanotechnology, the team developed a sponge with outstanding mercury adsorption properties where mercury contaminations can be removed from tap, lake and industrial wastewater to below detectable limits in less than 5 seconds (or around 5 minutes for industrial wastewater). The sponge converts the contamination into a non-toxic complex so it can be disposed of in a landfill after use. The sponge also kills bacterial and fungal microbes.

Think of it this way: If Como Lake in St. Paul was contaminated with mercury at the EPA limit, the sponge needed to remove all of the mercury would be the size of a basketball.

A March 16, 2017 University of Minnesota news release, which originated the news item, explains why this discovery is important for water supplies in the state of Minnesota,

This is an important advancement for the state of Minnesota, as more than two thirds of the waters on Minnesota’s 2004 Impaired Waters List are impaired because of mercury contamination that ranges from 0.27 to 12.43 ng/L (the EPA limit is 2 ng/L). Mercury contamination of lake waters results in mercury accumulation in fish, leading the Minnesota Department of Health to establish fish consumption guidelines. A number of fish species store-bought or caught in Minnesota lakes are not advised for consumption more than once a week or even once a month. In Minnesota’s North Shore, 10 percent of tested newborns had mercury concentrations above the EPA reference dose for methylmercury (the form of mercury found in fish). This means that some pregnant women in the Lake Superior region, and in Minnesota, have mercury exposures that need to be reduced.  In addition, a reduced deposition of mercury is projected to have economic benefits reflected by an annual state willingness-to-pay of $212 million in Minnesota alone.

According to the US-EPA, cutting mercury emissions to the latest established effluent limit standards would result in 130,000 fewer asthma attacks, 4,700 fewer heart attacks, and 11,000 fewer premature deaths each year. That adds up to at least $37 billion to $90 billion in annual monetized benefits annually.

In addition to improving air and water quality, aquatic life and public health, the new technology would have an impact on inspiring new regulations. Technology shapes regulations, which in turn determine the value of the market. The 2015 EPA Mercury and Air Toxics Standards regulation was estimated to cost the industry around of $9.6 billion annually in 2020. The new U of M technology has a potential of bringing this cost down and make it easy for the industry to meet regulatory requirements.

Research by Abbas and his team was funded by the MnDRIVE Global Food Venture, MnDRIVE Environment, and USDA-NIFA. They currently have three patents on this technology. To learn more, visit www.abbaslab.com.

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

A Nanoselenium Sponge for Instantaneous Mercury Removal to Undetectable Levels by Snober Ahmed, John Brockgreitens, Ke Xu, and Abdennour Abbas. Advanced Functional Materials DOI: 10.1002/adfm.201606572 Version of Record online: 6 MAR 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

STEM for refugees and disaster relief

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Just hours prior to the terrorist bombings in Paris (Friday, Nov. 13, 2015), Tash Reith-Banks published a Nov. 13, 2015 essay (one of a series) in the Guardian about science, technology, engineering, and mathematics (STEM) as those specialties apply to humanitarian aid with a special emphasis on Syrian refugee crisis.

This first essay focuses on how engineering and mathematics are essential when dealing with crises (from Reith-Banks’s Nov. 13, 2015 essay), Note: Links have been removed,

Engineering is a clear starting point: sanitation, shelter and supply lines are all essential in any crisis. As Martin McCann, CEO at RedR, which trains humanitarian NGO workers says: “There is the obvious work in providing water and sanitation and shelter. By shelter, we mean not only shelter or housing for disaster-affected people or refugees, but also structures to store both food and non-food items. Access is always critical, so once again engineers are needed to build roads or in some cases temporary landing strips.”

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Emergency structures need to be light and fast to transport and erect, but tend not to be durable. One recent development comes from engineers Peter Brewin and Will Crawford of Concrete Canvas., The pair have developed a rapid-setting concrete-impregnated fabric that requires only air and water to harden into a water-proof, fire-resistant construction. This has been used to create rapidly deployable concrete shelters that can be carried in a bag and set up in an hour.

Here’s what one of the concrete shelters looks like,

A Concrete Canvas shelter. Once erected the structure takes 24 hours to harden, and then can be further insulated with earth or snow if necessary. Photograph: Gareth Phillips/Gareth Phillips for the Guardian

A Concrete Canvas shelter. Once erected the structure takes 24 hours to harden, and then can be further insulated with earth or snow if necessary. Photograph: Gareth Phillips/Gareth Phillips for the Guardian

There are many kinds of crises which can lead to a loss of shelter, access to water and food, and diminished safety and health as Reith-Banks also notes in a passage featuring mathematics (Note: A link has been removed),

Maths might seem a far cry from the sort of practical innovation described above, but of course it’s the root of great logistics. Alistair Clark from the University of the West of England is using advanced mathematical modelling to improve humanitarian supply chains to ensure aid is sent exactly where it is needed. Part of the Newton Mobility scheme, Clark’s project will partner with Brazilian disaster relief agencies and develop ways of modelling everything from landslides to torrential downpours in order to create sophisticated humanitarian supply chains that can rapidly adapt to a range of possible disaster scenarios and changing circumstances.

In a similar vein, Professor Amr Elnashai, founder and co-editor of the Journal of Earthquake Engineering, works in earthquake-hit areas to plan humanitarian relief for future earthquakes. He recently headed a large research and development effort funded by the Federal Emergency Management Agency in the USA (FEMA), to develop a computer model of the impact of earthquakes on the central eight states in the USA. This included social impact, temporary housing allocation, disaster relief, medical and educational care, as well as engineering damage and its economic impact.

Reith-Banks also references nanotechnology (Note: A link has been removed),

… Up to 115 people die every hour in Africa from diseases linked to contaminated drinking water and poor sanitation, particularly in the wake of conflicts and environmental disasters. Dr Askwar Hilonga recently won the Royal Academy of Engineering Africa Prize, which is dedicated to African inventions with the potential to bring major social and economic benefits to the continent. Hilonga has invented a low cost, sand-based water filter. The filter combines nanotechnology with traditional sand-filtering methods to provide safe drinking water without expensive treatment facilities.  …

Dr. Hilonga who is based in Tanzania was featured here in a June 16, 2015 posting about the Royal Academy of Engineering Prize, his research, and his entrepreneurial efforts.

Reith-Banks’s* essay provides a valuable and unexpected perspective on the humanitarian crises which afflict this planet *and I’m looking forward to the rest of the series*.

*’Reith-Banks’s’ replaced ‘This’ and ‘and I’m looking forward to the rest of the series’ was added Nov. 17, 2015 at 1620 hours PST.

Graphene and water (G20 Water commentary)

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Tim Harper’s, Chief Executive Officer (CEO) of G2O Water, July 13, 2015 commentary was published on Nanotechnology Now. Harper, a longtime figure in the nanotechnology community (formerly CEO of Cientifica, an emerging technologies consultancy and current member of the World Economic Forum, not unexpectedly focused on water,

In the 2015 World Economic Forum’s Global Risks Report survey participants ranked Water Crises as the biggest of all risks, higher than Weapons of Mass Destruction, Interstate Conflict and the Spread of Infectious Diseases (pandemics). Our dependence on the availability of fresh water is well documented, and the United Nations World Water Development Report 2015 highlights a 40% global shortfall between forecast water demand and available supply within the next fifteen years. Agriculture accounts for much of the demand, up to 90% in most of the world’s least-developed countries, and there is a clear relationship between water availability, health, food production and the potential for civil unrest or interstate conflict.

The looming crisis is not limited to water for drinking or agriculture. Heavy metals from urban pollution are finding their way into the aquatic ecosystem, as are drug residues and nitrates from fertilizer use that can result in massive algal blooms. To date, there has been little to stop this accretion of pollutants and in closed systems such as lakes these pollutants are being concentrated with unknown long term effects.

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Ten years ago, following discussions with former Israeli Prime Minister Shimon Peres, I organised a conference in Amsterdam called Nanowater to look at how nanotechnology could address global water issues. [emphasis mine] While the meeting raised many interesting points, and many companies proposed potential solutions, there was little subsequent progress.

Rather than a simple mix of one or two contaminants, most real world water can contain hundreds of different materials, and pollutants like heavy metals may be in the form of metal ions that can be removed, but are equally likely to be bound to other larger pieces of organic matter which cannot be simply filtered through nanopores. In fact the biggest obstacle to using nanotechnology in water treatment is the simple fact that small holes are easily blocked, and susceptibility to fouling means that most nanopore membranes quickly become barriers instead of filters.

Fortunately some recent developments in the ‘wonder material’ graphene may change the economics of water. One of the major challenges in the commercialisation of graphene is the ability to create large areas of defect-free material that would be suitable for displays or electronics, and this is a major research topic in Europe where the European Commission is funding graphene research to the tune of a billion euros. …

Tim goes on to describe some graphene-based solutions including a technology developed at the University of South Carolina, which is also mentioned in a July 16, 2015 G20 Water press release,

Fouling of nano/ultrafiltration membranes in oil/water separation is a longstanding issue and a major economic barrier for their widespread adoption. Currently membranes typically show severe fouling, resulting from the strong adhesion of oil on the membrane surface and/or oil penetration inside the membranes. This greatly degrades their performance and shortens service lifetime as well as increasing the energy usage.

G2O™s bio inspired approach uses graphene oxide (GO) for the fabrication of fully-recoverable membranes for high flux, antifouling oil/water separation via functional and structural mimicking of fish scales. The ultra-thin, amphiphilic, water-locking GO coating mimics the thin mucus layer covering fish scales, while the combination of corrugated GO flakes and intrinsic roughness of the porous supports successfully reproduces the hierarchical roughness of fish scales. Cyclic membrane performance evaluation tests revealed circa 100% membrane recovery by facile surface water flushing, establishing their excellent easy-to-recover capability.

The pore sizes can be tuned to specific applications such as water desalination, oil/water separation, storm water treatment and industrial waste water recovery. By varying the GO concentration in water, GO membranes with different thickness can be easily fabricated via a one-time filtration process.
G2O™s patented graphene oxide technology acts as a functional coating for modifying the surface properties of existing filter media resulting in:
Higher pure water flux;
High fouling resistance;
Excellent mechanical strength;
High chemical stability;
Good thermal stability;
Low cost.

We’re going through a water shortage here in Vancouver, Canada after a long spring season which distinguished itself with a lack of rain and the introduction of a heatwave extending into summer. It is by no means equivalent to the situation in many parts of the world but it does give even those of us who are usually waterlogged some insight into what it means when there isn’t enough water.

For more insight into water crises with a special focus on the Middle East (notice Harper mentioned Israel’s former Prime Minister Shimon Peres in his commentary), I have a Feb. 24, 2014 posting (Water desalination to be researched at Oman’s newly opened Nanotechnology Laboratory at Sultan Qaboos University) and a June 25, 2013 post (Nanotechnology-enabled water resource collaboraton between Israel and Chicago).

You can check out the World Economic Forum’s Outlook on the Global Agenda 2015 here.

The Outlook on the Global Agenda 2015 features an analysis of the Top 10 trends which will preoccupy our experts for the next 12-18 months as well as the key challenges facing the world’s regions, an overview of global leadership and governance, and the emerging issues that will define our future.

G20 Water can be found here.