Category Archives: environment

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.

The Organization for Economic and Cooperative Development’s (OECD) test guidelines for nanomaterials

An Oct. 13, 2017 news item on Nanowerk announced news test guidelines from the Organization for Cooperation and Economic Development (OECD),

The OECD has released a first set of Test Guidelines developed specifically for nanomaterials, in response to their increased production and usage. The guidelines will help standardise the way countries test the safety of manufactured nanomaterials, whose near atomic-sized particles mean they may require more than regular chemical testing to understand their impact on health and the environment.

An Oct. 13, 2017 OECD press release (received via email), which originated the news item, provides more detail,

Test Guideline 318: Dispersion Stability of Nanomaterials in Simulated Environmental Media will help to assess how a particular nanomaterial would behave in contact with water or other liquids, making it applicable for testing nanomaterials likely to enter the natural environment, agriculture and food production, or to be in everyday skin contact with people through clothing or toiletries.

Additionally, updates to two existing Test Guidelines for inhalation toxicity studies (Guideline 412 and Guideline 413) mean they can now be used to determine the toxicity of inhaled nanomaterials.

The use of nanomaterials has skyrocketed of late, with manufacturers using them to improve performance in everything from tennis rackets to deodorant, yet nanoparticles can more easily penetrate skin, cells and the environment than larger compounds, and the increased likelihood of them entering the environment and human and animal bodies has raised concerns over their safety.

Working for 45 years to standardise methodologies for hazard testing and assessment, the OECD has produced over 160 harmonised test methods for determining physical and chemical properties, the effects of chemicals on health, wildlife and the environment, the efficacy of biocides and the chemistry of pesticide residues.

OECD Test Guidelines are used on a daily basis to test and assess the safety of industrial chemicals, pesticides and personal care products. They are part of the OECD’s Mutual Acceptance of Data programme, which saves over 150 million euros a year for its 42 signatory countries by avoiding duplication, as test data generated in one country is accepted by others having the same data requirement.

Journalists can download the new Test Guidelines for free on the OECD iLibrary at the links below using the OECD’s media log-in and password (available to media on request) or by email on request.

Test Guideline 318

Test Guideline 412

Test Guideline 413

OECD work on safety of manufactured nanomaterials www.oecd.org/chemicalsafety/nanosafety/

OECD work on chemical testing: www.oecd.org/chemicalsafety/testing/

For anyone who’s unaware of just how pervasive nanotechnology-enabled products have become, this brief OECD video illustrates the point nicely,

NanoFARM: food, agriculture, and nanoparticles

The research focus for the NanoFARM consortium is on pesticides according to an October 19, 2017 news item on Nanowerk,

The answer to the growing, worldwide food production problem may have a tiny solution—nanoparticles, which are being explored as both fertilizers and fungicides for crops.

NanoFARM – research consortium formed between Carnegie Mellon University [US], the University of Kentucky [US], the University of Vienna [Austria], and Aveiro University in Prague [Czech Republic] – is studying the effects of nanoparticles on agriculture. The four universities received grants from their countries’ respective National Science Foundations to discover how these tiny particles – some just 4 nanometers in diameter – can revolutionize how farmers grow their food.

An October ??, 2017 Carnegie Mellon University news release by Adam Dove, which originated the news item, fills in a few more details,

“What we’re doing is getting a fundamental understanding of nanoparticle-to-plant interactions to enable future applications,” says Civil and Environmental Engineering (CEE) Professor Greg Lowry, the principal investigator for the nanoFARM project. “With pesticides, less than 5% goes into the crop—the rest just goes into the environment and does harmful things. What we’re trying to do is minimize that waste and corresponding environmental damage by doing a better job of targeting the delivery.”

The teams are looking at related questions: How much nanomaterial is needed to help crops when it comes to driving away pests and delivering nutrients, and how much could potentially hurt plants or surrounding ecosystems?

Applied pesticides and fertilizers are vulnerable to washing away—especially if there’s a rainstorm soon after application. But nanoparticles are not so easily washed off, making them extremely efficient for delivering micronutrients like zinc or copper to crops.

“If you put in zinc oxide nanoparticles instead, it might take days or weeks to dissolve, providing a slow, long-term delivery system.”

Gao researches the rate at which nanoparticles dissolve. His most recent finding is that nanoparticles of copper oxide take up to 20-30 days to dissolve in soil, meaning that they can deliver nutrients to plants at a steady rate over that time period.

“In many developing countries, a huge number of people are starving,” says Gao. “This kind of technology can help provide food and save energy.”

But Gao’s research is only one piece of the NanoFARM puzzle. Lowry recently traveled to Australia with Ph.D. student Eleanor Spielman-Sun to explore how differently charged nanoparticles were absorbed into wheat plants.

They learned that negatively charged particles were able to move into the veins of a plant—making them a good fit for a farmer who wanted to apply a fungicide. Neutrally charged particles went into the tissue of the leaves, which would be beneficial for growers who wanted to fortify a food with nutritional value.

Lowry said they are still a long way from signing off on a finished product for all crops—right now they are concentrating on tomato and wheat plants. But with the help of their university partners, they are slowly creating new nano-enabled agrochemicals for more efficient and environmentally friendly agriculture.

For more information, you can find the NanoFARM website here.

Popping (nano)bubbles!

Who doesn’t love to pop bubbles? Well, there’s probably someone out there but it does seem to be a near universal delight (especially with the advent of bubble wrap which I’ve seen more than one person happily popping). Scientists are no more immune to that impulse than the rest of us although they approach the whole endeavour from a more technical perspective where popping bubbles becomes destabilization and bubble rupture. From a Sept. 28, 2017 American Institute of Physics (AIP) news release (also on EurekAlert),

Nanobubbles have recently gained popularity for their unique properties and expansive applications. Their large surface area and high stability in saturated liquids make nanobubbles ideal candidates for food science, medicine and environmental advancements. Nanobubbles also have long lifetimes of hours or days, and greater applicability than traditional macrobubbles, which typically only last for seconds.

The stability of nanobubbles is well understood, but the mechanisms causing their eventual destabilization are still in question. Using molecular dynamics simulations (MDS), researchers from the Beijing University of Chemical Technology explored the effect of surfactants — components that lower surface tension — on the stabilization of nanobubbles. They report their findings on the surprising mechanisms of destabilization [emphasis mine] for both soluble and insoluble surfactants this week [Sept. 25-29, 2017] in Applied Physics Letters, from AIP Publishing.

Researchers investigated the differences between soluble and insoluble surfactants and their varying influence on nanobubble stability using MDS software. They created a controled model system where the only variables that could be manipulated were the number of surfactants and the interaction between the surfactant and the substrate, the base of the model where the bubble is formed, to measure the direct influence of surfactants on nanobubble stability.

Analyzing both soluble and insoluble surfactants, the group focused on two possible mechanisms of destabilization: contact line depinning, where the surfactant flexibility reduces the forces responsible for stabilizing the bubble shape, causing it to rupture from lack of inner surface force; and surface tension reduction, causing a liquid to vapor phase transition.

The found soluble surfactants initiated nanobubble depinning when a large amount, roughly 80 percent, of the surfactant was adsorbed by the substrate, eventually causing the nanobubbles to burst.

“However, when small concentrations of soluble surfactant were introduced it remained dissolved, and adsorption onto the substrate was insignificant, generating a negligible effect on nanobubble stability,” said Xianren Zhang at Beijing University of Chemical Technology.

Simulations with insoluble surfactants showed comparable results to soluble surfactants when interacting heavily with substrates, but a new mechanism was discovered demonstrating a liquid-to-vapor transition model of bubble rupture [emphasis mine].

The transition is similar to how we traditionally envision bubbles popping, occurring when a surfactant significantly reduces the surface tension on the outside of the nanobubble. Nanobubbles destabilize in this fashion when a large amount of surfactant is present, but little — around 40 percent — surfactant-substrate interaction occurs.

These findings are critical to understanding nanobubble stability and have implications for nanobubble interaction with other molecules, including proteins and contaminants. Nanobubble applications could revolutionize aspects of modern medicine such as ultrasound techniques, expand functions in food science, and improve waste water treatment. But better characterizing basic properties like instability is essential to fully utilizing their potential in these applications.

There researchers have made this image illustrating their work available,

Several typical snapshots for nanobubbles losing their stability with various concentrations of surfactants and levels of interaction with substrates. In each picture, top panel shows evolution of the system with all involved particles, while in the bottom panel, solvent molecules are not shown to clarify the effect of surfactants. CREDIT: Qianxiang Xiao, Yawei Liu, Zhenjiang Guo, Zhiping Liu, and Xianren Zhang

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

How nanobubbles lose stability: Effects of surfactants featured by Qianxiang Xiao, Yawei Liu, Zhenjiang Guo, Zhiping Liua, and Xianren Zhang. Appl. Phys. Lett. 111, 131601 (2017); doi: http://dx.doi.org/10.1063/1.5000831

This paper is open access.

Plastic nanoparticles and brain damage in fish

Researchers in Sweden suggest plastic nanoparticles may cause brain damage in fish according to a Sept. 25, 2017 news item on phys.org,

Calculations have shown that 10 per cent of all plastic produced around the world ultimately ends up in the oceans. As a result, a large majority of global marine debris is in fact plastic waste. Human production of plastics is a well-known environmental concern, but few studies have studied the effects of tiny plastic particles, known as nanoplastic particles.

“Our study is the first to show that nanosized plastic particles can accumulate in fish brains”, says Tommy Cedervall, a chemistry researcher at Lund University.

A Sept. 25, 2017 Lund University press release, which originated the news item, provides more detail about the research,

The Lund University researchers studied how nanoplastics may be transported through different organisms in the aquatic ecosystem, i.e. via algae and animal plankton to larger fish. Tiny plastic particles in the water are eaten by animal plankton, which in turn are eaten by fish.

According to Cedervall, the study includes several interesting results on how plastic of different sizes affects aquatic organisms. Most importantly, it provides evidence that nanoplastic particles can indeed cross the blood-brain barrier in fish and thus accumulate inside fish’s brain tissue.

In addition, the researchers involved in the present study have demonstrated the occurrence of behavioural disorders in fish that are affected by nanoplastics. They eat slower and explore their surroundings less. The researchers believe that these behavioural changes may be linked to brain damage caused by the presence of nanoplastics in the brain.

Another result of the study is that animal plankton die when exposed to nanosized plastic particles, while larger plastic particles do not affect them. Overall, these different effects of nanoplastics may have an impact on the ecosystem as a whole.

“It is important to study how plastics affect ecosystems and that nanoplastic particles likely have a more dangerous impact on aquatic ecosystems than larger pieces of plastics”, says Tommy Cedervall.

However, he does not dare to draw the conclusion that plastic nanoparticles could accumulate in other tissues in fish and thus potentially be transmitted to humans through consumption.

“No, we are not aware of any such studies and are therefore very cautious about commenting on it”, says Tommy Cedervall.

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

Brain damage and behavioural disorders in fish induced by plastic nanoparticles delivered through the food chain by Karin Mattsson, Elyse V. Johnson, Anders Malmendal, Sara Linse, Lars-Anders Hansson & Tommy Cedervall. Scientific Reports 7, Article number: 11452 (2017) doi:10.1038/s41598-017-10813-0 Published online: 13 September 2017

This paper is open access.

A jellyfish chat on November 28, 2017 at Café Scientifique Vancouver get together

Café Scientifique Vancouver sent me an announcement (via email) about their upcoming event,

We are pleased to announce our next café which will happen on TUESDAY,
NOVEMBER 28TH at 7:30PM in the back room of YAGGER'S DOWNTOWN (433 W
Pender).

JELLYFISH – FRIEND, FOE, OR FOOD?

Did you know that in addition to stinging swimmers, jellyfish also cause
extensive damage to fisheries and coastal power plants? As threats such
as overfishing, pollution, and climate change alter the marine
environment, recent media reports are proclaiming that jellyfish are
taking over the oceans. Should we hail to our new jellyfish overlords or
do we need to examine the evidence behind these claims? Join Café
Scientifique on Nov. 28, 2017 to learn everything you ever wanted to
know about jellyfish, and find out if jelly burgers are coming soon to a
menu near you.

Our speaker for the evening will be DR. LUCAS BROTZ, a Postdoctoral
Research Fellow with the Sea Around Us at UBC’s Institute for the
Oceans and Fisheries. Lucas has been studying jellyfish for more than a
decade, and has been called “Canada’s foremost jellyfish
researcher” by CBC Nature of Things host Dr. David Suzuki. Lucas has
participated in numerous international scientific collaborations, and
his research has been featured in more than 100 media outlets including
Nature News, The Washington Post, and The New York Times. He recently
received the Michael A. Bigg award for highly significant student
research as part of the Coastal Ocean Awards at the Vancouver Aquarium.

We hope to see you there!

You can find out more about Lucas Brotz here and about Sea Around Us here.

For anyone who’s curious about the jellyfish ‘issue’, there’s a November 8, 2017 Norwegian University of Science and Technology press release on AlphaGallileo or on EurekAlert, which provides insight into the problems and the possibilities,

Jellyfish could be a resource in producing microplastic filters, fertilizer or fish feed. A new 6 million euro project called GoJelly, funded by the EU and coordinated by the GEOMAR Helmholtz Centre for Ocean Research, Germany and including partners at the Norwegian University of Science and Technology (NTNNU) and SINTEF [headquartered in Trondheim, Norway, is the largest independent research organisation in Scandinavia; more about SINTEF in its Wikipedia entry], hopes to turn jellyfish from a nuisance into a useful product.

Global climate change and the human impact on marine ecosystems has led to dramatic decreases in the number of fish in the ocean. It has also had an unforseen side effect: because overfishing decreases the numbers of jellyfish competitors, their blooms are on the rise.

The GoJelly project, coordinated by the GEOMAR Helmholtz Centre for Ocean Research, Germany, would like to transform problematic jellyfish into a resource that can be used to produce microplastic filter, fertilizer or fish feed. The EU has just approved funding of EUR 6 million over 4 years to support the project through its Horizon 2020 programme.

Rising water temperatures, ocean acidification and overfishing seem to favour jellyfish blooms. More and more often, they appear in huge numbers that have already destroyed entire fish farms on European coasts and blocked cooling systems of power stations near the coast. A number of jellyfish species are poisonous, while some tropical species are even among the most toxic animals on earth.

“In Europe alone, the imported American comb jelly has a biomass of one billion tons. While we tend to ignore the jellyfish there must be other solutions,” says Jamileh Javidpour of GEOMAR, initiator and coordinator of the GoJelly project, which is a consortium of 15 scientific institutions from eight countries led by the GEOMAR Helmholtz Centre for Ocean Research in Kiel.

The project will first entail exploring the life cycle of a number of jellyfish species. A lack of knowledge about life cycles makes it is almost impossible to predict when and why a large jellyfish bloom will occur. “This is what we want to change so that large jellyfish swarms can be caught before they reach the coasts,” says Javidpour.

At the same time, the project partners will also try to answer the question of what to do with jellyfish once they have been caught. One idea is to use the jellyfish to battle another, man-made threat.

“Studies have shown that mucus of jellyfish can bind microplastic. Therefore, we want to test whether biofilters can be produced from jellyfish. These biofilters could then be used in sewage treatment plants or in factories where microplastic is produced,” the GoJelly researchers say.

Jellyfish can also be used as fertilizers for agriculture or as aquaculture feed. “Fish in fish farms are currently fed with captured wild fish, which does not reduce the problem of overfishing, but increases it. Jellyfish as feed would be much more sustainable and would protect natural fish stocks,” says the GoJelly team.

Another option is using jellyfish as food for humans. “In some cultures, jellyfish are already on the menu. As long as the end product is no longer slimy, it could also gain greater general acceptance,” said Javidpour. Finally yet importantly, jellyfish contain collagen, a substance very much sought after in the cosmetics industry.

Project partners from the Norwegian University of Science and Technology, led by Nicole Aberle-Malzahn, and SINTEF Ocean, led by Rachel Tiller, will analyse how abiotic (hydrography, temperature), biotic (abundance, biomass, ecology, reproduction) and biochemical parameters (stoichiometry, food quality) affect the initiation of jellyfish blooms.

Based on a comprehensive analysis of triggering mechanisms, origin of seed populations and ecological modelling, the researchers hope to be able to make more reliable predictions on jellyfish bloom formation of specific taxa in the GoJelly target areas. This knowledge will allow sustainable harvesting of jellyfish communities from various Northern and Southern European populations.

This harvest will provide a marine biomass of unknown potential that will be explored by researchers at SINTEF Ocean, among others, to explore the possible ways to use the material.

A team from SINTEF Ocean’s strategic program Clean Ocean will also work with European colleagues on developing a filter from the mucus of the jellyfish that will catch microplastics from household products (which have their source in fleece sweaters, breakdown of plastic products or from cosmetics, for example) and prevent these from entering the marine ecosystem.

Finally, SINTEF Ocean will examine the socio-ecological system and games, where they will explore the potentials of an emerging international management regime for a global effort to mitigate the negative effects of microplastics in the oceans.

“Jellyfish can be used for many purposes. We see this as an opportunity to use the potential of the huge biomass drifting right in front of our front door,” Javidpour said.

You can find out more about GoJelly on their Twitter account.

Cellulose- and chitin-based biomaterial to replace plastics?

Although the term is not actually used in the news release, one of the materials used to create a new biomaterial could safely be described as nanocellulose. From a Sept. 20, 2017 Pennsylvania State University (Penn State) news release (also on EurekAlert) by Jeff Mulhollem,

An inexpensive biomaterial that can be used to sustainably replace plastic barrier coatings in packaging and many other applications has been developed by Penn State researchers, who predict its adoption would greatly reduce pollution.

Completely compostable, the material — a polysaccharide polyelectrolyte complex — is comprised of nearly equal parts of treated cellulose pulp from wood or cotton, and chitosan, which is derived from chitin — the primary ingredient in the exoskeletons of arthropods and crustaceans. The main source of chitin is the mountains of leftover shells from lobsters, crabs and shrimp consumed by humans.

These environmentally friendly barrier coatings have numerous applications ranging from water-resistant paper, to coatings for ceiling tiles and wallboard, to food coatings to seal in freshness, according to lead researcher Jeffrey Catchmark, professor of agricultural and biological engineering, College of Agricultural Sciences.

“The material’s unexpected strong, insoluble adhesive properties are useful for packaging as well as other applications, such as better performing, fully natural wood-fiber composites for construction and even flooring,” he said. “And the technology has the potential to be incorporated into foods to reduce fat uptake during frying and maintain crispness. Since the coating is essentially fiber-based, it is a means of adding fiber to diets.”

The amazingly sturdy and durable bond between carboxymethyl cellulose and chitosan is the key, he explained. The two very inexpensive polysaccharides — already used in the food industry and in other industrial sectors — have different molecular charges and lock together in a complex that provides the foundation for impervious films, coatings, adhesives and more.

The potential reduction of pollution is immense if these barrier coatings replace millions of tons of petroleum-based plastic associated with food packaging used every year in the United States — and much more globally, Catchmark noted.

He pointed out that the global production of plastic is approaching 300 million tons per year. In a recent year, more than 29 million tons of plastic became municipal solid waste in the U.S. and almost half was plastic packaging. It is anticipated that 10 percent of all plastic produced globally will become ocean debris, representing a significant ecological and human health threat.

crab shells

The material is comprised of cellulose pulp from wood or cotton, and chitosan, derived from chitin, the primary ingredient in the exoskeletons of arthropods and crustaceans. The main source of chitin is shells from lobsters, crabs and shrimp. Image: © iStock Photo OKRAD

The polysaccharide polyelectrolyte complex coatings performed well in research, the findings of which were published recently in Green Chemistry. Paperboard coated with the biomaterial, comprised of nanostructured fibrous particles of carboxymethyl cellulose and chitosan, exhibited strong oil and water barrier properties. The coating also resisted toluene, heptane and salt solutions and exhibited improved wet and dry mechanical and water vapor barrier properties.

“These results show that polysaccharide polyelectrolyte complex-based materials may be competitive barrier alternatives to synthetic polymers for many commercial applications,” said Catchmark, who, in concert with Penn State, has applied for a patent on the coatings.

“In addition, this work demonstrates that new, unexpected properties emerge from multi-polysaccharide systems engaged in electrostatic complexation, enabling new high-performance applications.”

Catchmark began experimenting with biomaterials that might be used instead of plastics a decade or so ago out of concerns for sustainability. He became interested in cellulose, the main component in wood, because it is the largest volume sustainable, renewable material on earth. Catchmark studied its nanostructure — how it is assembled at the nanoscale.

He believed he could develop natural materials that are more robust and improve their properties, so that they could compete with synthetic materials that are not sustainable and generate pollution — such as the low-density polyethylene laminate applied to paper board, Styrofoam and solid plastic used in cups and bottles.

“The challenge is, to do that you’ve got to be able to do it in a way that is manufacturable, and it has to be less expensive than plastic,” Catchmark explained. “Because when you make a change to something that is greener or sustainable, you really have to pay for the switch. So it has to be less expensive in order for companies to actually gain something from it. This creates a problem for sustainable materials — an inertia that has to be overcome with a lower cost.”

lab vials

The amazingly sturdy and durable bond between carboxymethyl cellulose and chitosan is the key. The two very inexpensive polysaccharides, already used in the food industry and in other industrial sectors, have different molecular charges and lock together in a complex that provides the foundation for impervious films, coatings, adhesives and more. Image: Penn State

Funded by a Research Applications for Innovation grant from the College of Agricultural Sciences, Catchmark currently is working to develop commercialization partners in different industry sectors for a wide variety of products.

“We are trying to take the last step now and make a real impact on the world, and get industry people to stop using plastics and instead use these natural materials,” he said. “So they (consumers) have a choice — after the biomaterials are used, they can be recycled, buried in the ground or composted, and they will decompose. Or they can continue to use plastics that will end up in the oceans, where they will persist for thousands of years.”

Also involved in the research were Snehasish Basu, post-doctoral scholar, and Adam Plucinski, master’s degree student, now instructor of engineering at Penn State Altoona. Staff in Penn State’s Material Research Institute provided assistance with the project.

The U.S. Department of Agriculture supported this work. Southern Champion Tray, of Chattanooga, Tennessee, provided paperboard and information on its production for experiments.

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

Sustainable barrier materials based on polysaccharide polyelectrolyte complexes by
Snehasish Basu, Adam Plucinski, and Jeffrey M. Catchmark. Green Chemistry 2017, 19, 4080-4092 DOI: 10.1039/C7GC00991G

This paper is behind a paywall. One comment, I found an anomaly on the page when I visited. At the top of the citation page, it states that this is issue 17 of Green Chemistry but the citation in the column on the right is “2017, 19 … “, which would be issue 19.

Substituting graphene and other carbon materials for scarce metals

A Sept. 19, 2017 news item on Nanowerk announces a new paper from the Chalmers University of Technology (Sweden), the lead institution for the Graphene Flagship (a 1B Euro 10 year European Commission programme), Note: A link has been removed,

Scarce metals are found in a wide range of everyday objects around us. They are complicated to extract, difficult to recycle and so rare that several of them have become “conflict minerals” which can promote conflicts and oppression. A survey at Chalmers University of Technology now shows that there are potential technology-based solutions that can replace many of the metals with carbon nanomaterials, such as graphene (Journal of Cleaner Production, “Carbon nanomaterials as potential substitutes for scarce metals”).

They can be found in your computer, in your mobile phone, in almost all other electronic equipment and in many of the plastics around you. Society is highly dependent on scarce metals, and this dependence has many disadvantages.

A Sept. 19, 2017 Chalmers University of Technology press release by Ulrika Ernstrom,, which originated the news item, provides more detail about the possibilities,

They can be found in your computer, in your mobile phone, in many of the plastics around you and in almost all electronic equipment. Society is highly dependent on scarce metals, and this dependence has many disadvantages.
Scarce metals such as tin, silver, tungsten and indium are both rare and difficult to extract since the workable concentrations are very small. This ensures the metals are highly sought after – and their extraction is a breeding ground for conflicts, such as in the Democratic Republic of the Congo where they fund armed conflicts.
In addition, they are difficult to recycle profitably since they are often present in small quantities in various components such as electronics.
Rickard Arvidsson and Björn Sandén, researchers in environmental systems analysis at Chalmers University of Technology, have now examined an alternative solution: substituting carbon nanomaterials for the scarce metals. These substances – the best known of which is graphene – are strong materials with good conductivity, like scarce metals.
“Now technology development has allowed us to make greater use of the common element carbon,” says Sandén. “Today there are many new carbon nanomaterials with similar properties to metals. It’s a welcome new track, and it’s important to invest in both the recycling and substitution of scarce metalsfrom now on.”
The Chalmers researchers have studied  the main applications of 14 different metals, and by reviewing patents and scientific literature have investigated the potential for replacing them by carbon nanomaterials. The results provide a unique overview of research and technology development in the field.
According to Arvidsson and Sandén the summary shows that a shift away from the use of scarce metals to carbon nanomaterials is already taking place.
….
“There are potential technology-based solutions for replacing 13 out of the 14 metals by carbon nanomaterials in their most common applications. The technology development is at different stages for different metals and applications, but in some cases such as indium and gallium, the results are very promising,” Arvidsson says.
“This offers hope,” says Sandén. “In the debate on resource constraints, circular economy and society’s handling of materials, the focus has long been on recycling and reuse. Substitution is a potential alternative that has not been explored to the same extent and as the resource issues become more pressing, we now have more tools to work with.”
The research findings were recently published in the Journal of Cleaner Production. Arvidsson and Sandén stress that there are significant potential benefits from reducing the use of scarce metals, and they hope to be able to strengthen the case for more research and development in the field.
“Imagine being able to replace scarce metals with carbon,” Sandén says. “Extracting the carbon from biomass would create a natural cycle.”
“Since carbon is such a common and readily available material, it would also be possible to reduce the conflicts and geopolitical problems associated with these metals,” Arvidsson says.
At the same time they point out that more research is needed in the field in order to deal with any new problems that may arise if the scarce metals are replaced.
“Carbon nanomaterials are only a relatively recent discovery, and so far knowledge is limited about their environmental impact from a life-cycle perspective. But generally there seems to be a potential for a low environmental impact,” Arvidsson says.

FACTS AND MORE INFORMATION

Carbon nanomaterials consist solely or mainly of carbon, and are strong materials with good conductivity. Several scarce metals have similar properties. The metals are found, for example, in cables, thin screens, flame-retardants, corrosion protection and capacitors.
Rickard Arvidsson and Björn Sandén at Chalmers University of Technology have investigated whether the carbon nanomaterials graphene, fullerenes and carbon nanotubes have the potential to replace 14 scarce metals in their main areas of application (see table). They found potential technology-based solutions to replace the metals with carbon nanomaterials for all applications except for gold in jewellery. The metals which we are closest to being able to substitute are indium, gallium, beryllium and silver.

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

Carbon nanomaterials as potential substitutes for scarce metals by Rickard Arvidsson, Björn A. Sandén. Journal of Cleaner Production (0959-6526). Vol. 156 (2017), p. 253-261. DOI: https://doi.org/10.1016/j.jclepro.2017.04.048

This paper appears to be open access.

Measurably fewer nanoparticles in São Paulo’s (Brazil) air after ethanol use

An Aug. 28, 2017 news item on Nanotechnology Now features news about nanoparticles and the environment in São Paulo, Brazil,

When ethanol prices at the pump rise for whatever reason, it becomes economically advantageous for drivers of dual-fuel vehicles to fill up with gasoline. However, the health of the entire population pays a high price: substitution of gasoline for ethanol leads to a 30% increase in the atmospheric concentration of ultrafine particulate matter, which consists of particles with a diameter of less than 50 nanometers (nm).

An Aug. 23, 2017 Fundação de Amparo à Pesquisa do Estado de São Paulo (The São Paulo Research Foundation [FAPESP]) press release, which originated the news item, explains further,

The phenomenon was detected in São Paulo City, Brazil, in a study supported by FAPESP and published in July 2017 in Nature Communications.

“These polluting nanoparticles are so tiny that they behave like gas molecules. When inhaled, they can penetrate the respiratory system’s defensive barriers and reach the pulmonary alveoli, so that potentially toxic substances enter the bloodstream and may increase the incidence of respiratory and cardiovascular problems,” said Paulo Artaxo, Full Professor at the University of São Paulo’s Physics Institute (IF-USP) and a co-author of the study.

Levels of ultrafine particulate matter in the atmosphere are neither monitored nor regulated by environmental agencies not only in Brazil but practically anywhere in the world, according to Artaxo. The São Paulo State Environmental Corporation (CETESB), for example, routinely monitors only solid particles with diameters of 10,000 nm (PM10) and 2,500 nm (PM2.5) – as well as other gaseous pollutants such as ozone (O3), carbon monoxide (CO) and nitrogen dioxide (NO2).

“Between 75% and 80% of the mass of the nanoparticles we measured in this study corresponds to organic compounds emitted by motor vehicles – carbon in different chemical forms. What these compounds are exactly and how they affect health are questions that require further research,” Artaxo said.

He added that a consensus is forming in the United States and Europe based on recent research indicating that these emissions are a potential health hazard and should be regulated. Several US states, such as California, have laws requiring a 20%-30% ethanol blend in gasoline, which also helps reduce emissions of ultrafine particulate matter.

Methodology

The data analyzed in the study were collected during the period of January-May 2011, when ethanol prices fluctuated sharply compared with gasoline prices, owing to macroeconomic factors such as variations in the international price of sugar (Brazilian ethanol is made from sugarcane).

Collection was performed at the top of a ten-story building belonging to IF-USP in the western part of São Paulo City. According to Artaxo, the site was chosen because it is relatively distant from the main traffic thoroughfares so that the aerosols there are “older” in the sense that they have already interacted with other substances present in the atmosphere.

“Generally speaking, the pollution we inhale every day at home or at work isn’t what comes out of vehicular exhaust pipes but particles already processed in the atmosphere,” he explained. “For this reason, we chose a site that isn’t directly impacted by primary vehicle emissions.”

The study was conducted during Joel Ferreira de Brito’s postdoctoral research, which Artaxo supervised. The model used to analyze the data was developed by Brazilian economist Alberto Salvo, a professor at the National University of Singapore and first author of the article. Franz Geiger, a chemist at Northwestern University in the US, also collaborated.

“We adapted a sophisticated statistical model originally developed for economic analysis and used here for the first time to analyze the chemistry of atmospheric nanoparticles,” Artaxo said. “The main strength of this tool is that it can work with a large number of variables, such as the presence or absence of rainfall, wind direction, traffic intensity, and levels of ozone, carbon monoxide and other pollutants.”

Analyses were performed before, during and after a sharp fluctuation in ethanol prices leading consumers to switch motor fuels in São Paulo City. While no significant changes were detected in levels of inhalable fine particulate matter (PM2.5 and PM10), the study proved in a real, day-to-day situation that choosing ethanol reduces emissions of ultrafine particles. To date, this phenomenon had only been observed in the laboratory.

“These results reinforce the need for public policies to encourage the use of biofuels, as they clearly show that the public lose in health what they save at the pump when opting for gasoline,” Artaxo said.

In São Paulo, a city with 7 million motor vehicles and the largest urban fleet of flexible-fuel cars, it would be feasible to run all buses on biofuel. “We have the technology for this in Brazil – and at a competitive price,” he said.

The fact that the city’s bus fleet still depends on diesel, Artaxo warned, creates an even worse health hazard in the shape of emissions of black carbon, one of the main components of soot and a pollutant that contributes to global warming. Alongside electricity generation, the transportation sector is the largest emitter of pollutants produced by the burning of fossil fuels.

For Artaxo, incentives for electric, hybrid or biofuel vehicles are vital to reduce greenhouse gas emissions. “By incentivizing biofuels, we could solve several problems at once,” he said. “We could combat climate change, reduce harm to health and foster advances in automotive technology by offering a stimulus for auto makers to develop more economical and efficient cars fueled by ethanol.”

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

Reduced ultrafine particle levels in São Paulo’s atmosphere during shifts from gasoline to ethanol use by Alberto Salvo, Joel Brito, Paulo Artaxo, & Franz M. Geiger. Nature Communications 8, Article number: 77 (2017) doi:10.1038/s41467-017-00041-5 Published online: 18 July 2017

This paper is open access.

Getting a more complete picture of aerosol particles at the nanoscale

What is in the air we breathe? In addition to the gases we learned about in school there are particles, not just the dust particles you can see, but micro- and nanoparticles too and scientists would like to know more about them.

An August 23, 2017 news item on Nanowerk features work which may help scientists in their quest,

They may be tiny and invisible, says Xiaoji Xu, but the aerosol particles suspended in gases play a role in cloud formation and environmental pollution and can be detrimental to human health.

Aerosol particles, which are found in haze, dust and vehicle exhaust, measure in the microns. One micron is one-millionth of a meter; a thin human hair is about 30 microns thick.

The particles, says Xu, are among the many materials whose chemical and mechanical properties cannot be fully measured until scientists develop a better method of studying materials at the microscale as well as the much smaller nanoscale (1 nm is one-billionth of a meter).

Xu, an assistant professor of chemistry, has developed such a method and utilized it to perform noninvasive chemical imaging of a variety of materials, as well as mechanical mapping with a spatial resolution of 10 nanometers.

The technique, called peak force infrared (PFIR) microscopy, combines spectroscopy and scanning probe microscopy. In addition to shedding light on aerosol particles, Xu says, PFIR will help scientists study micro- and nanoscale phenomena in a variety of inhomogeneous materials.

The lower portion of this image by Xiaoji Xu’s group shows the operational scheme of peak force infrared (PFIR) microscopy. The upper portion shows the topography of nanoscale PS-b-PMMA polymer islands on a gold substrate. (Image courtesy of Xiaoji Xu)

An August 22, 2017 Lehih University news release by Kurt Pfitzer (also on EurekAlert), which originated the news item, explains the research in more detail (Note: A link has been removed),

“Materials in nature are rarely homogeneous,” says Xu. “Functional polymer materials often consist of nanoscale domains that have specific tasks. Cellular membranes are embedded with proteins that are nanometers in size. Nanoscale defects of materials exist that affect their mechanical and chemical properties.

“PFIR microscopy represents a fundamental breakthrough that will enable multiple innovations in areas ranging from the study of aerosol particles to the investigation of heterogeneous and biological materials,” says Xu.

Xu and his group recently reported their results in an article titled “Nanoscale simultaneous chemical and mechanical imaging via peak force infrared microscopy.” The article was published in Science Advances, a journal of the American Association for the Advancement of Science, which also publishes Science magazine.

The article’s lead author is Le Wang, a Ph.D. student at Lehigh. Coauthors include Xu and Lehigh Ph.D. students Haomin Wang and Devon S. Jakob, as well as Martin Wagner of Bruker Nano in Santa Barbara, Calif., and Yong Yan of the New Jersey Institute of Technology.

“PFIR microscopy enables reliable chemical imaging, the collection of broadband spectra, and simultaneous mechanical mapping in one simple setup with a spatial resolution of ~10 nm,” the group wrote.

“We have investigated three types of representative materials, namely, soft polymers, perovskite crystals and boron nitride nanotubes, all of which provide a strong PFIR resonance for unambiguous nanochemical identification. Many other materials should be suited as well for the multimodal characterization that PFIR microscopy has to offer.

“In summary, PFIR microscopy will provide a powerful analytical tool for explorations at the nanoscale across wide disciplines.”

Xu and Le Wang also published a recent article about the use of PFIR to study aerosols. Titled “Nanoscale spectroscopic and mechanical characterization of individual aerosol particles using peak force infrared microscopy,” the article appeared in an “Emerging Investigators” issue of Chemical Communications, a journal of the Royal Society of Chemistry. Xu was featured as one of the emerging investigators in the issue. The article was coauthored with researchers from the University of Macau and the City University of Hong Kong, both in China.

PFIR simultaneously obtains chemical and mechanical information, says Xu. It enables researchers to analyze a material at various places, and to determine its chemical compositions and mechanical properties at each of these places, at the nanoscale.

“A material is not often homogeneous,” says Xu. “Its mechanical properties can vary from one region to another. Biological systems such as cell walls are inhomogeneous, and so are materials with defects. The features of a cell wall measure about 100 nanometers in size, placing them well within range of PFIR and its capabilities.”

PFIR has several advantages over scanning near-field optical microscopy (SNOM), the current method of measuring material properties, says Xu. First, PFIR obtains a fuller infrared spectrum and a sharper image—6-nm spatial resolution—of a wider variety of materials than does SNOM. SNOM works well with inorganic materials, but does not obtain as strong an infrared signal as the Lehigh technique does from softer materials such as polymers or biological materials.

“Our technique is more robust,” says Xu. “It works better with soft materials, chemical as well as biological.”

The second advantage of PFIR is that it can perform what Xu calls point spectroscopy.

“If there is something of interest chemically on a surface,” Xu says, “I put an AFM [atomic force microscopy] probe to that location to measure the peak-force infrared response.

“It is very difficult to obtain these spectra with current scattering-type scanning near-field optical microscopy. It can be done, but it requires very expensive light sources. Our method uses a narrow-band infrared laser and costs about $100,000. The existing method uses a broadband light source and costs about $300,000.”

A third advantage, says Xu, is that PFIR obtains a mechanical as well as a chemical response from a material.

“No other spectroscopy method can do this,” says Xu. “Is a material rigid or soft? Is it inhomogeneous—is it soft in one area and rigid in another? How does the composition vary from the soft to the rigid areas? A material can be relatively rigid and have one type of chemical composition in one area, and be relatively soft with another type of composition in another area.

“Our method simultaneously obtains chemical and mechanical information. It will be useful for analyzing a material at various places and determining its compositions and mechanical properties at each of these places, at the nanoscale.”

A fourth advantage of PFIR is its size, says Xu.

“We use a table-top laser to get infrared spectra. Ours is a very compact light source, as opposed to the much larger sizes of competing light sources. Our laser is responsible for gathering information concerning chemical composition. We get mechanical information from the AFM [atomic force microscope]. We integrate the two types of measurements into one device to simultaneously obtain two channels of information.”

Although PFIR does not work with liquid samples, says Xu, it can measure the properties of dried biological samples, including cell walls and protein aggregates, achieving a 10-nm spatial resolution without staining or genetic modification.

This looks like very exciting work.

Here are links and citations for both studies mentioned in the news release (the most recently published being cited first),

Nanoscale simultaneous chemical and mechanical imaging via peak force infrared microscopy by Le Wang, Haomin Wang, Martin Wagner, Yong Yan, Devon S. Jakob, and Xiaoji G. Xu. Science Advances 23 Jun 2017: Vol. 3, no. 6, e1700255 DOI: 10.1126/sciadv.1700255

Nanoscale spectroscopic and mechanical characterization of individual aerosol particles using peak force infrared microscopy by Le Wang, Dandan Huang, Chak K. Chan, Yong Jie Li, and Xiaoji G. Xu. Chem. Commun., 2017,53, 7397-7400 DOI: 10.1039/C7CC02301D First published on 16 Jun 2017

The June 23, 2017 paper is open access while the June 16, 2017 paper is behind a paywall.