You are browsing the archives of 2011 February.

Credit: Piccolo Namek, Wikipedia.

I really had intended to give the topic of LEDs a rest for a while. But while catching up on some reading, I came across a story suggesting that, while LEDs have performance advantages over incandescents and CFLs, one can’t assume that LEDs are free from disposal problems. In fact, the paper’s authors from the University of California (Davis and Irvine) suggest that LEDs may bring their own “environmental burdens.”

The researchers, who are associated with UCI’s School of Social Ecology/Program in Public Health and UCD’s Department of Chemical Engineering and Materials Science, distinguish between environmental burdens related to resource depletion (e.g., gold and silver) and those burdens related to toxicity (e.g., copper, nickel and lead).

The groups goals was to test whether LEDs could be considered “hazardous wastes” as defined by United States and California standards, look at how the threat might vary across different LED types and look at the overall life-cycle impact of LEDs. The latter was done, in part, to help designers and manufacturers make safer products and to help waste disposers and recyclers know how to handle LEDs that are already making their way to landfills.

Their findings, published in Environmental Science & Technology, were that some LEDs did pose a threat of leaching toxic materials if disposed of improperly, but the threat was largely related to LED color and intensity. In fact, with one exception, all LEDs exceeded Cali’s silver, nickel, lead and copper standards. The one exception is low-intensity yellow LEDs. One type of LED — low-intensity reds — exceeded federal lead standards.

The groups methods were pretty straight forward: Grind up LEDs and expose the resultant flecks, nuggets and specks to the equivalent of multiyear bath in acid rain, and then test for toxic materials in the runoff.

This isn’t the first time these researchers have used this type of approach. For example, UCI’s Oladele A. Ogunseitan has been grinding up and testing cell phones and other commercial electronics for some time. Ogunseitan has been the principal investigator in NSF-sponsored study on strategies for addressing e-wastes. Another group member, UCD’s Julie M. Shoenung, runs the school’s Lead Campus activities that are part of the Research and Education in Green Materials program.

In an online story, Gizmag writer Darren Quick, reports:

Ogunseitan blames the situation on a lack of proper product testing before LEDs were presented as a more efficient replacement for incandescent bulbs - which are now being phased out around the world. Although a law requiring more stringent testing for such products was scheduled to begin on January 1st in California, it was opposed by industry groups, and Governor Arnold Schwarzenegger put it on hold before leaving office.

“Every day we don’t have a law that says you cannot replace an unsafe product with another unsafe product, we’re putting people’s lives at risk,” said Ogunseitan. “And it’s a preventable risk.”

One point of this group’s work is that the time to act is now. LEDs were already entering the waste stream from auto industry applications (front and rear lights) and hitting the mass market in the form of cheap and ubiquitous holiday lights.

On a practical level, the group suggests that anyone having to clean up broken LEDs should treat the situation as if approaching broken CFLs. Wear gloves, mask and use special brooms and other equipment to gather the debris. They also go so far as to suggest special precautions for emergency responders to highway accidents.

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Worth a look:

‘Rechargeable’ anti-microbial surfaces boost food safety

A University of Massachusetts Amherst food scientist is developing a way to improve food safety by adding a thin anti-microbial layer to food-handling surfaces. Only tens of nanometers thick, it chemically “re-charges” its germ-killing powers every time it’s rinsed with common household bleach.

Overview of NIST’s Polymers Division

Established in 1962, the Polymers Division in the Material Measurement Laboratory of the National Institute of Standards and Technology will soon celebrate its 50th year as a world leader in polymers research.

Moth eye-inspired antireflective material boosts efficiency of solar cells

Researchers at Nagaoka University of Technology (Japan), Mitsubishi Rayon Co. Ltd. and Tokyo Metropolitan University pioneered a way to use anodic porous alumina molds to nanoimprint the microstructure similar to a moth’s eye into acrylic resin. The film could boost solar cell efficiency 5-6 percent.

Torque vectoring gears for smaller, more efficient wind turbines

Gigmag’s Darren Quick reports that investigators at the Technische Universitaet Muenchen “have now adapted this technology to wind turbines, to eliminate the need for converting the alternating current produced by the turbines into direct current and back again before it is fed into the grid.”

Second wave of ‘cleantech’ investing coming?

GigaOM’s Katie Fehrenbacher reports on what may be a renaissance in venture capital firms’ interest in clean and green technologies. What might be guiding their way this time? A) Being more realistic about how long commercialization takes; B) Look for opportunities outside the U.S., such as China, Brazil, India and even Europe.

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Change in the wt percent of hydrogen in few-layer graphene sample created via exfoliation (EG) and arc evaporation of graphite under hydrogen (HGH). (Inset) The evolution of hydrogen as recorded by gas chromatograph. Credit: Subrahmanyam et al.

A group of researchers from the Jawaharlal Nehru Center for Advanced Scientific Research in Bangalore, India say they have come across a new approach for using graphene for hydrogen storage. They say in a paper published in the Proceedings of the National Academy of Sciences they have been able to create samples containing up to 5 wt percent hydrogen, which they say can be completely released through heating or by irradiating with a laser or UV light source. For comparison purposes, the maximum amount of hydrogen that can be contained in graphene is 7.7 wt percent.

This isn’t the first time researchers have looked at graphene. Much of this work has been done in the context of trying to find some sort of suitable solid body for hydrogen storage. Previously, some investigators began thinking about carbon nanotubes. Some storage effects were achieved, but overall the results have been disappointing.

Other research also has been done at Columbia University using single-layer graphene showing that hydrogenation can occur and be reversed through a photothermal heating process, but apparently the amount of hydrogen that is stored in the single layer was not measured (the work was focused on methods to manipulate the charge transport properties of the graphene).

The JNCASR group, led by C.N.R. Rao, looked at additional research that suggested that hydrogen loading might be better accomplished through the use of multiple layers of graphene, and decided to do some detailed studies in this area.

In brief, the group used two methods to form few-layer graphene samples: exfoliation of graphite oxide (forming 6–7 layers) and arc evaporation of graphite under hydrogen (forming 2–3 layers). The researchers hydrogenated both samples (using Birch reduction), and both samples displayed a hydrogen content of approximately 5 wt percent.

They found that the hydrogen-containing graphene is stable at room temperature “and can be stored over long periods.”

When the samples are heated, the hydrogen begins to be released around 200°C and is totally released at 500°C. As mentioned above, they also used laser and UV irradiation to break the C–H bonds and free the hydrogen.

The group feels this storage system may have potential applications, and that a better storage system may be achievable. The authors note, “Although Birch reduction enabled us to incorporate 5 wt percent of hydrogen in few-layer graphenes, it may be possible to carry out hydrogenation more effectively by other methods.” They also report they have achieved 3 wt percent storage using graphene nanoribbons, which also fully releases its hydrogen at 500°C.

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Printing solar cells. Credit: Nanosolar.

I received a note from the organizers of Green Technologies for Materials Manufacturing and Processing symposium that will be part of this fall’s Materials Science & Technology 2011 conference. Tatsuki Ohji (National Institute of Advanced Industrial Science), Mrityunjay Singh (Ohio Aerospace Institute, NASA Glenn Research Center), Richard D. Sisson (Worcester Polytechnic Institute, Center for Heat Treating Excellence) and Makio Naito (Osaka University) say they are excited about the interest that has been shown in recent years about this symposisum (2011 marks the third time it will have been held), and they want to remind everyone that the deadline for submitting abstracts is March 15, 2011.

The organizers frame the symposium like this:

Sustainable development is globally recognized as a key issue for future society. Therefore, green, or environmentally-benign technology, should be the focus for materials scientists and engineers. Generally, two issues are substantially important. One is to avoid unnecessary use and generation of compounds directly hazardous to human health and the environment, such as heavy metals and persistent organic pollutants. The other is to protect the global environment by preserving energy and conserving natural resources during the fabrication. The volumes of consumed raw materials, used energy (or emitted carbon dioxide) and disposed wastes are indicative of sustainability of the process.

Keeping these two aspects in view, this symposium deals with a variety of green technologies related with materials manufacturing and processing that are feasible in the industry. Topics to be discussed in this symposium include environmental impact of materials, products and processes; development of alternative technologies; waste minimization technologies and instrumentation development. Topics will also include the identification of green opportunities and/or upfront solutions to environmental problems in these or related processes, as well as recent initiatives and developments in education in green engineering.

If you are interested in presenting in this symposium, shoot off an abstract to the organizers by submitting your concept online here.

MS&T’11 will occur in Columbus, Ohio, Oct. 16–20, 2011.

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Ultra-high temperature materials are required in hypersonic aerospace applications, such as NASA’s X-51A vehicle. Credit: NASA.

Netzsch Instruments has announced that it is launching what I assume it hopes to be a regularly occurring conference on high-temperature materials, applications, testing, processing and diagnostics. Netzsch is calling the inaugural meeting “Hi Temp 2011″ and will hold it in Boston, Mass., Sept. 20-22.

According to the Netzsch website, Hi Temp 2011 “will include presentations of cutting edge results on materials such as, thermoelectric materials, thermal barriers, piezoelectric, nuclear reactor materials, radioactive waste, high temperature ceramics, catalyst, insulating materials.”

Netzsch says there will be a lot of focus on state-of-the-art characterization methods and thermal analysis. In terms of scope of the meeting, Netzsch says it intends to cover the following topics:

• Energy applications
• Aerospace applications
• Melts, glass and amorphous materials
• Thermal and structural properties measurement in ceramics and thin films
• Processing-property relations in dielectric and piezoelectric ceramics
• Thermoelectric materials
• Ultra-high temperature ceramic multilayer coatings
• Construction materials

Readers can download a conference brochure here (PDF).

Netzsch makes thermal analysis instruments for  thermophysical properties measurement.

Boston is usually gorgeous that time of the year and the Red Sox are playing in town Sept. 21 and 22!

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