Tag Archives: decontamination

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

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.

Nanomaterials and UV (ultraviolet) light for environmental cleanups

I think this is the first time I’ve seen anything about a technology that removes toxic materials from both water and soil; it’s usually one or the other. A July 22, 2015 news item on Nanowerk makes the announcement (Note: A link has been removed),

Many human-made pollutants in the environment resist degradation through natural processes, and disrupt hormonal and other systems in mammals and other animals. Removing these toxic materials — which include pesticides and endocrine disruptors such as bisphenol A (BPA) — with existing methods is often expensive and time-consuming.

In a new paper published this week in Nature Communications (“Nanoparticles with photoinduced precipitation for the extraction of pollutants from water and soil”), researchers from MIT [Massachusetts Institute of Technology] and the Federal University of Goiás in Brazil demonstrate a novel method for using nanoparticles and ultraviolet (UV) light to quickly isolate and extract a variety of contaminants from soil and water.

A July 21, 2015 MIT news release by Jonathan Mingle, which originated the news item, describes the inspiration and the research in more detail,

Ferdinand Brandl and Nicolas Bertrand, the two lead authors, are former postdocs in the laboratory of Robert Langer, the David H. Koch Institute Professor at MIT’s Koch Institute for Integrative Cancer Research. (Eliana Martins Lima, of the Federal University of Goiás, is the other co-author.) Both Brandl and Bertrand are trained as pharmacists, and describe their discovery as a happy accident: They initially sought to develop nanoparticles that could be used to deliver drugs to cancer cells.

Brandl had previously synthesized polymers that could be cleaved apart by exposure to UV light. But he and Bertrand came to question their suitability for drug delivery, since UV light can be damaging to tissue and cells, and doesn’t penetrate through the skin. When they learned that UV light was used to disinfect water in certain treatment plants, they began to ask a different question.

“We thought if they are already using UV light, maybe they could use our particles as well,” Brandl says. “Then we came up with the idea to use our particles to remove toxic chemicals, pollutants, or hormones from water, because we saw that the particles aggregate once you irradiate them with UV light.”

A trap for ‘water-fearing’ pollution

The researchers synthesized polymers from polyethylene glycol, a widely used compound found in laxatives, toothpaste, and eye drops and approved by the Food and Drug Administration as a food additive, and polylactic acid, a biodegradable plastic used in compostable cups and glassware.

Nanoparticles made from these polymers have a hydrophobic core and a hydrophilic shell. Due to molecular-scale forces, in a solution hydrophobic pollutant molecules move toward the hydrophobic nanoparticles, and adsorb onto their surface, where they effectively become “trapped.” This same phenomenon is at work when spaghetti sauce stains the surface of plastic containers, turning them red: In that case, both the plastic and the oil-based sauce are hydrophobic and interact together.

If left alone, these nanomaterials would remain suspended and dispersed evenly in water. But when exposed to UV light, the stabilizing outer shell of the particles is shed, and — now “enriched” by the pollutants — they form larger aggregates that can then be removed through filtration, sedimentation, or other methods.

The researchers used the method to extract phthalates, hormone-disrupting chemicals used to soften plastics, from wastewater; BPA, another endocrine-disrupting synthetic compound widely used in plastic bottles and other resinous consumer goods, from thermal printing paper samples; and polycyclic aromatic hydrocarbons, carcinogenic compounds formed from incomplete combustion of fuels, from contaminated soil.

The process is irreversible and the polymers are biodegradable, minimizing the risks of leaving toxic secondary products to persist in, say, a body of water. “Once they switch to this macro situation where they’re big clumps,” Bertrand says, “you won’t be able to bring them back to the nano state again.”

The fundamental breakthrough, according to the researchers, was confirming that small molecules do indeed adsorb passively onto the surface of nanoparticles.

“To the best of our knowledge, it is the first time that the interactions of small molecules with pre-formed nanoparticles can be directly measured,” they write in Nature Communications.

Nano cleansing

Even more exciting, they say, is the wide range of potential uses, from environmental remediation to medical analysis.

The polymers are synthesized at room temperature, and don’t need to be specially prepared to target specific compounds; they are broadly applicable to all kinds of hydrophobic chemicals and molecules.

“The interactions we exploit to remove the pollutants are non-specific,” Brandl says. “We can remove hormones, BPA, and pesticides that are all present in the same sample, and we can do this in one step.”

And the nanoparticles’ high surface-area-to-volume ratio means that only a small amount is needed to remove a relatively large quantity of pollutants. The technique could thus offer potential for the cost-effective cleanup of contaminated water and soil on a wider scale.

“From the applied perspective, we showed in a system that the adsorption of small molecules on the surface of the nanoparticles can be used for extraction of any kind,” Bertrand says. “It opens the door for many other applications down the line.”

This approach could possibly be further developed, he speculates, to replace the widespread use of organic solvents for everything from decaffeinating coffee to making paint thinners. Bertrand cites DDT, banned for use as a pesticide in the U.S. since 1972 but still widely used in other parts of the world, as another example of a persistent pollutant that could potentially be remediated using these nanomaterials. “And for analytical applications where you don’t need as much volume to purify or concentrate, this might be interesting,” Bertrand says, offering the example of a cheap testing kit for urine analysis of medical patients.

The study also suggests the broader potential for adapting nanoscale drug-delivery techniques developed for use in environmental remediation.

“That we can apply some of the highly sophisticated, high-precision tools developed for the pharmaceutical industry, and now look at the use of these technologies in broader terms, is phenomenal,” says Frank Gu, an assistant professor of chemical engineering at the University of Waterloo in Canada, and an expert in nanoengineering for health care and medical applications.

“When you think about field deployment, that’s far down the road, but this paper offers a really exciting opportunity to crack a problem that is persistently present,” says Gu, who was not involved in the research. “If you take the normal conventional civil engineering or chemical engineering approach to treating it, it just won’t touch it. That’s where the most exciting part is.”

The researchers have made this illustration of their work available,

Nanoparticles that lose their stability upon irradiation with light have been designed to extract endocrine disruptors, pesticides, and other contaminants from water and soils. The system exploits the large surface-to-volume ratio of nanoparticles, while the photoinduced precipitation ensures nanomaterials are not released in the environment. Image: Nicolas Bertrand Courtesy: MIT

Nanoparticles that lose their stability upon irradiation with light have been designed to extract endocrine disruptors, pesticides, and other contaminants from water and soils. The system exploits the large surface-to-volume ratio of nanoparticles, while the photoinduced precipitation ensures nanomaterials are not released in the environment.
Image: Nicolas Bertrand Courtesy: MIT

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

Nanoparticles with photoinduced precipitation for the extraction of pollutants from water and soil by Ferdinand Brandl, Nicolas Bertrand, Eliana Martins Lima & Robert Langer. Nature Communications 6, Article number: 7765 doi:10.1038/ncomms8765 Published 21 July 2015

This paper is open access.

Nanotechnology and site remediation; nano company gives aid to Haiti; nano commodity exchange; new Canadian photovoltaic research network; sensual nanotechnology

Tomorrow morning, Feb. 4, 2010, the Project on Emerging Nanotechnologies (PEN) will be webcasting an event titled, Contaminated Site Remediation: Are Nanomaterials the Answer? It starts at 9:30 am PST and the webcast can accessed from here.  Unfortunately I won’t be able to attend the live webcast but I will try to listen to it when they post the feed on their site a few days later. I did post more information, including a link to PEN’s site remediation map, about this event here.

More or less coincident with this event and on a somewhat related note, there is a donation from the company Nanoscale to relief efforts in Haiti. From the news item on Azonano,

NanoScale’s products and expertise in chemical and biological decontamination will provide protection and odor control to those most affected. NanoScale has donated NanoZorb®, a portable decomposition decontamination system based on products originally developed for U.S. military decontamination applications, to selected groups to aid their recovery efforts.

While it is likely as much a public relations effort as relief, bravo!

I’ve come across many comments as to how nanotechnology could be helpful to the environment but most of the examples I’ve seen are in the energy sector (i.e., ways nanotechnology-enabled products can reduce energy use). I’m hopeful these site remediation and decontamination nanotechnology efforts will be helpful and won’t become future problems.

There is a new commodities exchange on the horizon, Integrated Nano-Science Commodity Exchange (INSCX). From the news item on Nanowerk,

INSCX™ – Integrated Nano-Science Commodity Exchange, a patent-pending project to develop a global commodity exchange platform for trade in nano objects, materials and commodities, has formalised an agreement with AssuredNano™ [SHE] to co-ordinate the global accreditation of supply onto the market platform which is scheduled to launch in the UK early 2011.

AssuredNano™ is the premier Safety, Health and Environment (SHE) accreditation scheme for organisations producing nanomaterials, nano-enabled products and users of nanotechnology in general. It promotes the responsible and proactive application of nanomaterial SHE good current practice within the nanomaterials and nanotechnology community.

INSCX™, is designed to provide the “hub to the wheel of nanotechnologies” where the interests of business can co-exist with those of state governments, regional authorities, specialist agencies, research bodies, and consumer groups to deliver ethical and commercial cohesion across nanotechnologies.

I’m trying to figure out how AssuredNano can supply accreditation when there are no internationally accepted standard definitions for terms such as nanomaterials. (The International Standards Organization [ISO] has developed definitions but I have not seen any indication that they have been adopted as standards.) The AssuredNano site does not provide any details about their accreditation scheme, as you can see for yourself here. I hope to see more detailed information before the exhange starts in 2011.

As I noted earlier, most of the nanotechnology environmental news is focused on energy. Canada’s Natural Sciences and Engineering Research Council (NSERC) just this week announced the establishment of a new solar photovoltaic research network headquartered at McMaster University. From the news item on physorg.com,

The Natural Sciences and Engineering Research Council of Canada (NSERC) announced $5 million in funding today for the establishment of the NSERC Photovoltaic Innovation Network. The Network is comprised of 29 top scientists and engineers working in the field of advanced solar cell research at 13 universities across Canada. Eleven private sector companies are also part of the network.

The Network aims to raise the status of solar photovoltaics (PV) as a renewable energy option in Canada by accelerating research and development and commercializing the outcomes.

Now on a completely different note, the sensual side of nanotechnology. From the news item on Nanowerk,

Pin-sharp projections, light that’s whiter than white, varnishes that make sounds if the temperature changes: at nano tech 2010 in Tokyo, Fraunhofer researchers present nanotechnology that is a veritable feast for the senses.

A mystical glow emanates from the display case. A white light appears out of nowhere. And a light source is invisible – at least at first glance. Only upon close examination does the source of the apparently supernatural illumination become visible: a light diode, smaller than a pinhead, passes through thousands of infinitesimal lens structures measuring only a few hundred nanometers, et voilà: beaming white light.

Nanotechnology not only puts an entirely new dimension before the eye, it also makes audible things that no ear could ever perceive before: like changes in temperature. A new varnish developed by researchers at the Fraunhofer Institute for Engineering and Automation IPA ensures that surfaces emit sound if they become warmer or cool off. The trick: carbon nano-tubes embedded in the varnish that conduct electricity …

In addition to sight and sound, I have one more sense to cover, touch. From the news item, Multitouch ‘Skin’ Transforms Surfaces into Interactive Screens, on physorg.com,

The DISPLAX Multitouch Technology, believed to be the first of its kind, has been developed based on a transparent thinner-than-paper polymer film. When applied to glass, plastic or wood, the surface becomes interactive. Significantly, this new multitouch technology can be applied to standard LCD screens as well, making it an attractive choice for LCD manufacturers. The new technology will also be available for audiovisual integrators or gaming platforms to develop innovative products.

The DISPLAX Multitouch Technology dramatically extends the capabilities of the interactive format. It can be applied to flat or curved, opaque as well as transparent surfaces up to three metres across the diagonal. It is hyper sensitive, allowing users to interact with an enabled surface not just by touching it but, for the first time, by blowing on it, opening up new possibilities for future applications. Currently, the technology can detect up to 16 fingers on a 50-inch screen. The number of fingers detected is expected to increase as development progresses.

It may take a while before pure white light or varnish that you can hear comes to market but the multitouch ‘skin’ is here as a harbinger of what is to come. Offhand, I’m not sure I want to hear varnish. It seems to me that it would be like having an alarm that I can’t shut off  which means I could be confronted with any number of products that are emitting sounds because they are too hot or too cold or nearing the end of their product lives or, worse yet, malfunctioning.