Tag Archives: iron nanoparticles

The Swiss come to a better understanding of nanomaterials

Just to keep things interesting, after the report suggesting most of the information that the OECD (Organization for Economic Cooperation and Development) has on nanomaterials is of little value for determining risk (see my April 5, 2017 posting for more) the Swiss government has released a report where they claim an improved understanding of nanomaterials than they previously had due to further research into the matter. From an April 6, 2017 news item on Nanowerk,

In the past six years, the [Swiss] National Research Programme “Opportunities and Risks of Nanomaterials” (NRP 64) intensively studied the development, use, behaviour and degradation of engineered nanomaterials, including their impact on humans and on the environment.

Twenty-three research projects on biomedicine, the environment, energy, construction materials and food demonstrated the enormous potential of engineered nanoparticles for numerous applications in industry and medicine. Thanks to these projects we now know a great deal more about the risks associated with nanomaterials and are therefore able to more accurately determine where and how they can be safely used.

An April 6, 2017 Swiss National Science Foundation press release, which originated the news item, expands on the theme,

“One of the specified criteria in the programme was that every project had to examine both the opportunities and the risks, and in some cases this was a major challenge for the researchers,” explains Peter Gehr, President of the NRP 64 Steering Committee.

One development that is nearing industrial application concerns a building material strengthened with nanocellulose that can be used to produce a strong but lightweight insulation material. Successful research was also carried out in the area of energy, where the aim was to find a way to make lithium-ion batteries safer and more efficient.

Promising outlook for nanomedicine

A great deal of potential is predicted for the field of nanomedicine. Nine of the 23 projects in NRP 64 focused on biomedical applications of nanoparticles. These include their use for drug delivery, for example in the fight against viruses, or as immune modulators in a vaccine against asthma. Another promising application concerns the use of nanomagnets for filtering out harmful metallic substances from the blood. One of the projects demonstrated that certain nanoparticles can penetrate the placenta barrier, which points to potential new therapy options. The potential of cartilage and bone substitute materials based on nanocellulose or nanofibres was also studied.

The examination of potential health risks was the focus of NRP 64. A number of projects examined what happens when nanoparticles are inhaled, while two focused on ingestion. One of these investigated whether the human gut is able to absorb iron more efficiently if it is administered in the form of iron nanoparticles in a food additive, while the other studied silicon nanoparticles as they occur in powdered condiments. It was ascertained that further studies will be required in order to determine the doses that can be used without risking an inflammatory reaction in the gut.

What happens to engineered nanomaterials in the environment?

The aim of the seven projects focusing on environmental impact was to gain a better understanding of the toxicity of nanomaterials and their degradability, stability and accumulation in the environment and in biological systems. Here, the research teams monitored how engineered nanoparticles disseminate along their lifecycle, and where they end up or how they can be discarded.

One of the projects established that 95 per cent of silver nanoparticles that are washed out of textiles are collected in sewage treatment plants, while the remaining particles end up in sewage sludge, which in Switzerland is incinerated. In another project a measurement device was developed to determine how aquatic microorganisms react when they come into contact with nanoparticles.

Applying results and making them available to industry

“The findings of the NRP 64 projects form the basis for a safe application of nanomaterials,” says Christoph Studer from the Federal Office of Public Health. “It has become apparent that regulatory instruments such as testing guidelines will have to be adapted at both national and international level.” Studer has been closely monitoring the research programme in his capacity as the Swiss government’s representative in NRP 64. In this context, the precautionary matrix developed by the government is an important instrument by means of which companies can systematically assess the risks associated with the use of nanomaterials in their production processes.

The importance of standardised characterisation and evaluation of engineered nanomaterials was highlighted by the close cooperation among researchers in the programme. “The research network that was built up in the framework of NRP 64 is functioning smoothly and needs to be further nurtured,” says Professor Bernd Nowack from Empa, who headed one of the 23 projects.

The results of NRP 64 show that new key technologies such as the use of nanomaterials need to be closely monitored through basic research due to the lack of data on its long-term effects. As Peter Gehr points out, “We now know a lot more about the risks of nanomaterials and how to keep them under control. However, we need to conduct additional research to learn what happens when humans and the environment are exposed to engineered nanoparticles over longer periods, or what happens a long time after a one-off exposure.”

You can find out more about the Opportunities and Risks of Nanomaterials; National Research Programme (NRP 64) here.

NanoRem: pollution, nanotechnology, and remediation

According to a July 6, 2013 news item on Nanowerk, nanoremediation is not the right term for referring to pollution cleanup technologies that are nanotechnology-enabled,

In the remediation of pollutions in the soil and groundwater, minute nanoparticles are being increasingly used that are to convert resp. break down pollutants on site. The process, often somewhat mistakenly described as “nano-remediation”, can also be used with contaminations that have been hard to fight up to now, for example through heavy metals or the notorious, carcinogenic softener PCB. Yet how do the various nanoparticles behave in the earth, are they in turn harmless for humans and the environment and how can they be produced at a favourable price? These questions were investigated by scientists from the Research Facility for Subsurface Remediation (VEGAS) of the University of Stuttgart together with 27 partners from 13 countries in the framework of EU project “NanoRem”, planned to last four years. For this purpose the European Union is providing around 10.5 million Euros from the 7th research framework programme.

The July 6, 2013 news item on Nanotechnology Now (ordinarily, I’d quote from the University of Stuttgart press release which originated the Nanowerk and Nanotechnology Now news items but the university’s website seems to be experiencing technical problems) provides more details about treating pollution with ‘nanotechnology-enabled’ techniques and more information about NanoRem,

Nanotechnologies are particularly suited for treating groundwater aquifers but also contaminated soil at the site of the contamination (in situ). However, in remediation projects (reclamation of contaminated sites), they have only been used hesitantly since an effective and reliable application is not yet mature, the potential risks for the environment difficult to assess and nano-remediation in addition comparatively expensive due to the still high manufacturing costs of nanoparticles. The nanotechnology, however, offers advantages: compared to the classic remediation processes, such as “Pump & Treat” (pumping off contaminated groundwater and cleaning it in a treatment plant) or chemical, resp. microbiological in-situ remediation processes, the range of “treatable” contaminants is greater. In addition, a quick and targeted break down of pollutants can be achieved, for example also in industrial buildings without the production being interrupted. “Through nanotechnology we are expecting a significant improvement in the remediation service and the operational areas”, according to the Stuttgart coordinator Dr. Hans-Peter Koschitzky. This would not only be beneficial for the environment but would also be attractive from an economical point of view: the world market for the application of environmental nanotechnologies was estimated to be a total of six billion US Dollars in 2010.

Against this background the scientists involved in NanoRem want to develop practical, efficient, safe and economical nanotechnologies for in-situ remediation with the aim of enabling a commercial use as well as a spread of the application in Europe. The focus is on the best-suited nanotechnologies as well as favourably priced production techniques. For this purpose questions on the mobility and reactivity of nanoparticles in the subsoil as well as the possible risk potential for mankind and environment in particular are to be investigated. A further aim is the provision of a comprehensive “tool box” for the planning and monitoring of the remediation as well as success control.

The Stuttgart researchers will be focusing on the use of nanoscale iron particles (aka, nano zero valent iron nZVI?; you can find out more about zNVI in my Mar. 20, 2012 posting) as per the news items,

The researchers from the Stuttgart Research Facility for Subsurface Remediation, VEGAS, are concentrating on the large-scale implementation of nano-iron particles within the project. Initially three large-scale tests are conducted: artificial aquifers are established with defined sand layers of various properties in large stainless steel containers in the experimental hall and flooded with groundwater. In each of these large-scale tests a defined source of pollution is incorporated, then various nanoparticles are injected. Probes in the container provide information on the concentrations of pollutants and nanoparticles as well as on the remediation progress at many sites in the aquifer. These tests are validated by Dutch and Italian partners with the help of a numerical groundwater flow and transport model. Finally, field tests at sites in need of remediation with various requirement profiles are conducted in several countries in Europe in order to verify the efficiency and profitability of nano-remediation. In particular, however, they also serve the purpose of achieving acceptance through transparency Europe-wide with public authorities and the public.

There is more information about the NanoRem project on the CORDIS website. The NanoRem website is currently (July 8, 2013) under construction but does offer more overview information on its landing page.

Canadian and Japanese researchers create new technique for using iron nanoparticles in greener hydrogenation process

McGill University’s Audrey Moores and her team’s latest green chemistry work with researchers at RIKEN (The Institute of Physical and Chemical Research, Wako, Japan) and the Institute for Molecular Science (Okazaki, Japan) is featured in a June 27, 2013 news item on Nanowerk,

Researchers from McGill University, RIKEN (The Institute of Physical and Chemical Research, Wako, Japan) and the Institute for Molecular Science (Okazaki, Japan) have discovered a way to make the widely used chemical process of hydrogenation more environmentally friendly – and less expensive.

Hydrogenation is a chemical process used in a wide range of industrial applications, from food products, such as margarine, to petrochemicals and pharmaceuticals. The process typically involves the use of heavy metals, such as palladium or platinum, to catalyze the chemical reaction. While these metals are very efficient catalysts, they are also non-renewable, costly, and subject to sharp price fluctuations on international markets.

Because these metals are also toxic, even in small quantities, they also raise environmental and safety concerns. Pharmaceutical companies, for example, must use expensive purification methods to limit residual levels of these elements in pharmaceutical products. Iron, by contrast, is both naturally abundant and far less toxic than heavy metals.

Previous work by other researchers has shown that iron nanoparticles — tiny pieces of metallic iron — can be used to activate the hydrogenation reaction. Iron, however, has a well-known drawback: it rusts in the presence of oxygen or water. When rusted, iron nanoparticles stop acting as hydrogenation catalysts. This problem, which occurs with so much as trace quantities of water, has prevented iron nanoparticles from being used in industry.

The June 27, 2013 McGill University news release on EurekAlert, which originated the news item, provides details about the new technique,

The key to this new method is to produce the particles directly inside a polymer matrix, composed of amphiphilic polymers based on polystyrene and polyethylene glycol. The polymer acts as a wrapping film that protects the iron surface from rusting in the presence of water, while allowing the reactants to reach the water and react.

This innovation enabled the researchers to use iron nanoparticles as catalyst in a flow system, raising the possibility that iron could be used to replace platinum-series metals for hydrogenation under industrial conditions.

“Our research is now focused on achieving a better understanding of how the polymers are protecting the surface of the iron from water, while at the same time allowing the iron to interact with the substrate,” says Audrey Moores, an assistant professor of chemistry at McGill and co-corresponding author of the paper.

“The approach we have developed through this collaboration could lead to more sustainable industrial processes,” says Prof. Uozumi [Prof. Yasuhiro Uozumi of Riken]. “This technique provides a system in which the reaction can happen over and over with the same small amount of a catalytic material, and it enables it to take place in almost pure water — the green solvent par excellence.”

I last wrote about greener chemistry and iron nanoparticles in a March 28, 2012 posting concerning some work at the University of Toronto while the last time McGill, green chemistry, and Audrey Moores were mentioned here was in a Jan. 10, 2011 posting concerning ‘nanomagnetics.

For those who are interested in this latest work from McGill, here’s a link to and a citation for the published paper,

Highly efficient iron(0) nanoparticle-catalyzed hydrogenation in water in flow by Reuben Hudson, Go Hamasaka, Takao Osako, Yoichi M. A. Yamada, Chao-Jun Li, Yasuhiro Uozumi, and Audrey Moores.
Green Chem., 2013, Advance Article DOI: 10.1039/C3GC40789F

First published online 27 Jun 2013

This paper is behind a paywall.

Magnetically cleaning up oil spills

Researchers at the Massachusetts Institute of Technology (MIT) have developed a promising technique for cleaning up oil spills, using magnets, which is more efficient and more environmentally friendly.

ETA Sept. 14, 2012: For some reason the embedded video keeps disappearing, so here’s the link: http://youtu.be/ZaP7XOjsCHQ

The Sept. 12, 2012 news item on Nanowerk notes,

The researchers will present their work at the International Conference on Magnetic Fluids in January. Shahriar Khushrushahi, a postdoc in MIT’s Department of Electrical Engineering and Computer Science, is lead author on the paper, joined by Markus Zahn, the Thomas and Gerd Perkins Professor of Electrical Engineering, and T. Alan Hatton, the Ralph Landau Professor of Chemical Engineering. The team has also filed two patents on its work.

In the MIT researchers’ scheme, water-repellent ferrous nanoparticles would be mixed with the oil, which could then be separated from the water using magnets. The researchers envision that the process would take place aboard an oil-recovery vessel, to prevent the nanoparticles from contaminating the environment. Afterward, the nanoparticles could be magnetically removed from the oil and reused.

Larry Hardesty’s Sept. 12, 2012 MIT news release , which originated the news item, provides detail about the standard technique for  using magnetic nanoparticles and the new technique,

According to Zahn, there’s a good deal of previous research on separating water and so-called ferrofluids — fluids with magnetic nanoparticles suspended in them. Typically, these involve pumping a water-and-ferrofluid mixture through a channel, while magnets outside the channel direct the flow of the ferrofluid, perhaps diverting it down a side channel or pulling it through a perforated wall.

This approach can work if the concentration of the ferrofluid is known in advance and remains constant. But in water contaminated by an oil spill, the concentration can vary widely. Suppose that the separation system consists of a branching channel with magnets along one side. If the oil concentration were zero, the water would naturally flow down both branches. By the same token, if the oil concentration is low, a lot of the water will end up flowing down the branch intended for the oil; if the oil concentration is high, a lot of the oil will end up flowing down the branch intended for the water.

The MIT researchers vary the conventional approach in two major ways: They orient their magnets perpendicularly to the flow of the stream, not parallel to it; and they immerse the magnets in the stream, rather than positioning them outside of it.

The magnets are permanent magnets, and they’re cylindrical. Because a magnet’s magnetic field is strongest at its edges, the tips of each cylinder attract the oil much more powerfully than its sides do. In experiments the MIT researchers conducted in the lab, the bottoms of the magnets were embedded in the base of a reservoir that contained a mixture of water and magnetic oil; consequently, oil couldn’t collect around them. The tops of the magnets were above water level, and the oil shot up the sides of the magnets, forming beaded spheres around the magnets’ ends.

The design is simple, but it provides excellent separation between oil and water. Moreover, Khushrushahi says, simplicity is an advantage in a system that needs to be manufactured on a large scale and deployed at sea for days or weeks, where electrical power is scarce and maintenance facilities limited

. …

In their experiments, the MIT researchers used a special configuration of magnets, called a Halbach array, to extract the oil from the tops of the cylindrical magnets. When attached to the cylinders, the Halbach array looks kind of like a model-train boxcar mounted on pilings. The magnets in a Halbach array are arranged so that on one side of the array, the magnetic field is close to zero, but on the other side, it’s roughly doubled. In the researchers’ experiments, the oil in the reservoir wasn’t attracted to the bottom of the array, but the top of the array pulled the oil off of the cylindrical magnets.

While this work is promising, there are still a lot of issues to be addressed including how water will be removed from the recovered oil (oil and water can mix to some degree depending on their relative densities).

Greener catalysts with iron nanoparticles

A research team at the University of Toronto has announced the discovery of a possible ‘green’ alternative to commonly used catalysts in the food, drug, and fragrance industries. From the March 27, 2012 news item on Nanowerk,

A chemistry team at the University of Toronto has discovered environmentally-friendly iron-based nanoparticle catalysts that work as well as the expensive, toxic, metal-based catalysts that are currently in wide use by the drug, fragrance and food industry.

“It is always important to strive to make industrial syntheses more green, and using iron catalysts is not only much less toxic, but it is also much more cost effective,” said Jessica Sonnenberg, a PhD student and lead author of a paper published this week in the Journal of the American Chemical Society (“Iron Nanoparticles Catalyzing the Asymmetric Transfer Hydrogenation of Ketones”).

The March 27, 2012 University of Toronto news release provides a quote from Sonnenberg which suggests there’s still a lot more work to be done before the toxic metal-based catalysts currently being used could be replaced,

… “Catalysts, even cheap iron ones developed for these types of reaction, still suffer one major downfall,” explained Sonnenberg.  “They require a one-to-one ratio of very expensive organic ligands – the molecule that binds to the central metal atom of a chemical compound – to yield catalytic activity. Our discovery of functional surface nanoparticles opens the door to using much smaller ratios of these expensive compounds relative to the metal centres.  This drastically reduces the overall cost of the transformations.”

This work at the University of Toronto reminded me of another team also working on green catalysts for chemical reactions and also based in Canada, this time at McGill University. The McGill team lead by Chao-Jun Li was mentioned most recently here in a Jan. 10, 2011 posting where their ‘nanomagnetics’ technology to replace the current toxic catalysts  is described.