Purdue University: New chemical conversion process turns plastic waste into fuel

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One of the biggest problems facing the Earth’s environment right now is the abundance of plastic waste. An estimated 5 billion tons of plastic is collecting in landfills or filling the oceans, and if not addressed, it will plague the decades to come by degrading into toxic chemicals, polluting the land and sea and destroying the habitats of wildlife. As scientific research looks for a solution, one possible option is trying to turn the waste into a usable fuel source.

A groups of chemists from Purdue University have developed a new process that can convert common types of plastic into a fuel similar to gasoline and diesel. Their research, recently published in ACS Sustainable Chemistry and Engineering, details how polypropylene, which is often found in toys, medical devices, and food packaging, can be converted into a fuel pure enough to be used in motor vehicles.

The researchers explain that their conversion process uses supercritical water, or water that has the characteristics of both a liquid and a gas based on pressure and temperature conditions. Specifically, they heated water until it was between 716 and 932 degrees Fahrenheit, with pressures that were 2,300 times that found at sea level. It was discovered that purified polypropylene would turn into oil when added to this mix, with the conversion process taking less than an hour at 850 degrees Fahrenheit.

Polypropylene is said to make up roughly a quarter of the world’s 5 billion tons of plastic waste, but lead researcher Linda Wang believes their new process could convert 90% of polypropylene into fuel. There’s no word on how or when this conversion process might be widely implemented, but Wang says the recycling industry should be motivated to move quickly, as the fuel it produces can be sold for a profit.


With carbon nanotubes, a path to flexible, low-cost sensors

Nano Particles for Steel 324x182(Nanowerk News) Researchers at the Technische  Universitaet Muenchen (TUM) are showing the way toward low-cost,  industrial-scale manufacturing of a new family of electronic devices. A leading  example is a gas sensor that could be integrated into food packaging to gauge  freshness, or into compact wireless air-quality monitors. New types of solar  cells and flexible transistors are also in the works, as well as pressure and  temperature sensors that could be built into electronic skin for robotic or  bionic applications. All can be made with carbon nanotubes, sprayed like ink  onto flexible plastic sheets or other substrates.
Carbon nanotube-based gas sensors created at TUM offer a unique  combination of characteristics that can’t be matched by any of the alternative  technologies. They rapidly detect and continuously respond to extremely small  changes in the concentrations of gases including ammonia, carbon dioxide, and  nitrogen oxide. They operate at room temperature and consume very little power.  Furthermore, as the TUM researchers report in their latest papers, such devices  can be fabricated on flexible backing materials through large-area, low-cost  processes.
Flexible carbon nanotube Gas Sensors
Flexible, high-performance gas sensors (left) were made by spraying  a solution of carbon nanotubes (right) onto a plastic backing.
Thus it becomes realistic to envision plastic food wrap that  incorporates flexible, disposable gas sensors, providing a more meaningful  indicator of food freshness than the sell-by date. Measuring carbon dioxide, for  example, can help predict the shelf life of meat. “Smart packaging” – assuming  consumers find it acceptable and the devices’ non-toxic nature can be  demonstrated – could enhance food safety and might also vastly reduce the amount  of food that is wasted. Used in a different setting, the same sort of gas sensor  could make it less expensive and more practical to monitor indoor air quality in  real time.
Not so easy – but “really simple”
Postdoctoral researcher Alaa Abdellah and colleagues at the TUM  Institute for Nanoelectronics have demonstrated that high-performance gas  sensors can be, in effect, sprayed onto flexible plastic substrates. With that,  they may have opened the way to commercial viability for carbon nanotube-based  sensors and their applications. “This really is simple, once you know how to do  it,” says Prof. Paolo Lugli, director of the institute.
The most basic building block for this technology is a single  cylindrical molecule, a rolled-up sheet of carbon atoms that are linked in a  honeycomb pattern. This so-called carbon nanotube could be likened to an  unimaginably long garden hose: a hollow tube just a nanometer or so in diameter  but perhaps millions of times as long as it is wide. Individual carbon nanotubes  exhibit amazing and useful properties, but in this case the researchers are more  interested in what can be done with them en masse.
Laid down in thin films, randomly oriented carbon nanotubes form  conductive networks that can serve as electrodes; patterned and layered films  can function as sensors or transistors. “In fact,” Prof. Lugli explains, “the  electrical resistivity of such films can be modulated by either an applied  voltage (to provide a transistor action) or by the adsorption of gas molecules,  which in turn is a signature of the gas concentration for sensor applications.”
And as a basis for gas sensors in particular, carbon nanotubes  combine advantages (and avoid shortcomings) of more established materials, such  as polymer-based organic electronics and solid-state metal-oxide semiconductors.  What has been lacking until now is a reliable, reproducible, low-cost  fabrication method.
Spray deposition, supplemented if necessary by transfer  printing, meets that need. An aqueous solution of carbon nanotubes looks like a  bottle of black ink and can be handled in similar ways. Thus devices can be  sprayed – from a computer-controlled robotic nozzle – onto virtually any kind of  substrate, including large-area sheets of flexible plastic. There is no need for  expensive clean-room facilities.
“To us it was important to develop an easily scalable technology  platform for manufacturing large-area printed and flexible electronics based on  organic semiconductors and nanomaterials,” Dr. Abdellah says. “To that end,  spray deposition forms the core of our processing technology.”
Remaining technical challenges arise largely from  application-specific requirements, such as the need for gas sensors to be  selective as well as sensitive.
Fabrication of carbon nanotube thin films on  flexible substrates by spray deposition and transfer printing. Ahmed  Abdelhalim, Alaa Abdellah, Giuseppe Scarpa, Paolo Lugli. Carbon, Vol.  61, September 2013, 72-79.
Flexible carbon nanotube-based gas sensors  fabricated by large-scale spray deposition. Alaa Abdellah, Zubair Ahmad,  Philipp Köhler, Florin Loghin, Alexander Weise, Giuseppe Scarpa, Paolo Lugli.  IEEE Sensors Journal, Vol. 13 Issue 10, October 2013, 4014-4021.
Scalable spray deposition process for high  performance carbon nanotube gas sensors. Alaa Abdellah, Ahmed Abdelhalim,  Markus Horn, Giuseppe Scarpa, and Paolo Lugli. IEEE Transactions on  Nanotechnology 12, 174-181, 2013.
Source: Technische Universität München 

Read more: http://www.nanowerk.com/news2/newsid=32464.php#ixzz2fyQreLnJ

Printing Ultrafast Graphene Chips for Flexible Electronics

Futurists are always talking about how flexible electronics will change our lives in amazing ways, but we’ve yet to see anything mind-blowing come to market. A team of scientists from the University of Texas in Austin, however, think they’ve found the key to changing that: ultrafast graphene transistors printed on flexible plastic.

Graphene is amazing. Or at least, it could be. Made from a layer of carbon one-atom thick, it’s the strongest material in the world, it’s… Read…

   9 Incredible Uses for Graphene

Graphene is amazing stuff for a lot different reasons. One reason is that it’s the perfect material for chip-making, and conventional graphene chips have broken several electronic speed records. In the past, however, attempts to put graphene transistors on flexible materials have caused that speed to take a dive. Not with this new method.

Indeed, the chips from Texas clock in at a record-breaking 25-gigahertz. The MIT Technology Review explains the manufacturing process:

To make the transistors, the researchers first fabricate all the non-graphene-containing structures—the electrodes and gates that will be used to switch the transistors on and off—on sheets of plastic. Separately, they grow large sheets of graphene on metal, then peel it off and transfer it to complete the devices. …

The graphene transistors are not only speedy but robust. The devices still work after being soaked in water, and they’re flexible enough to be folded up.

And things are only getting better. Earlier this week we learned about a cutting edge technique for making graphene chips developed by a team of researchers from the University of California.

All we need now is a company to take the plunge and start bringing some of this next level technology to market. And you thought Liquidmetal was cool !!     [Technology Review]


Scientists Just Figured Out How to Make Lightning-Fast Graphene CPUs

Graphene has the power to change computing forever by making the fastest transistors ever. In theory. We just haven’t figured out how yet. Sound familiar? Fortunately, scientists have just taken a big step closer to making graphene transistors work for real.

Graphene transistors aren’t just fast; they’re lightning fast. The speediest one to date clocked in at some 427 GHz. That’s orders of magnitude more than what you can tease out of today’s processors.  The problem with graphene transistors, though, is that they aren’t particularly good at turning off. They don’t turn off at all actually, which makes it hard to use them as switches.