Over on WUWT there was a posting about Graphene membranes potentially leading to dramatic reduction in the cost of desalinizing water. Interesting, and likely to lead to a whole lot of places that are not presently habitable becoming a great place to live and grow crops.
OK, very important to mankind and to life and the world economy and all…
but it’s just water…
Then there was an interesting article linked by Crosspatch in the new battery thread per the creation of large (DVD sized) sheets of graphene using a regular old DVD burner. Cheap and scalable mass production possible.
But what caught my attention was a link from the wiki on Graphene talking about how it lets water through, but nothing else. Say what?
In comments on the WUWT thread I’d speculated that odd things were likely down at the molecular scale; and got dumped on by a couple of folks insisting that things would be unchanged from regular scale… somehow thinking my statement was against the laws of thermodynamics or some such. I specifically stated that the laws of thermo would always hold, but they seemed to take that to mean “nothing unexpected” will happen.
Well, it sure looks to me like this article is saying unusual things happen at that scale!
Unimpeded permeation of water through helium-leak-tight graphene-based membranes
R. R. Nair, H. A. Wu, P. N. Jayaram, I. V. Grigorieva, A. K. Geim
(Submitted on 15 Dec 2011)
Permeation through nanometer pores is important in the design of materials for filtration and separation techniques and because of unusual fundamental behavior arising at the molecular scale. We found that submicron-thick membranes made from graphene oxide can be completely impermeable to liquids, vapors and gases, including helium, but allow unimpeded permeation of water (H2O permeates through the membranes at least 10^10 times faster than He). We attribute these seemingly incompatible observations to a low-friction flow of a monolayer of water through two dimensional capillaries formed by closely spaced graphene sheets. Diffusion of other molecules is blocked by reversible narrowing of the capillaries in low humidity and/or by their clogging with water.
You can download the whole PDF here:
This is seriously interesting…
Among other things, it means that water can easily be removed from things. Like fermented mash. Vodka on the cheap, in terms of energy. An entirely new economics to ethanol fuel production.
So not only can you separate water from salt, but also water from ethanol. One presumes ‘water from other stuff’ too.
It is also curiously odd that even helium doesn’t get through. Very strange.
“The measurements set up an upper limit on ΠHe of GO laminates as ≈10^‐15 mm×g/cm^2×s×bar, that is, our submicrometre‐thick films provide a higher gas barrier than 1‐millimeter‐thick glass”
Golly. “Glass” like obstruction of gasses, but water flows through… I can see a real market for a hand held one of these for cleaning and desalinizing drinking water in emergency kits and on ships. (Can I patent that idea now? ;-)
Heck, in the desert you could pee in it and get pure water back.
Or, as the wiki described it:
Room temperature distillation of ethanol for fuel and human consumption
Graphene oxide membranes will allow water vapor to pass through, but have been shown to be impermeable to all other liquids and gases including helium . This phenomenon has been used for further distilling of vodka to higher alcohol concentrations, in a room-temperature laboratory, without the application of heat or vacuum normally used in traditional distillation methods. Further development and commercialization of such membranes could revolutionize the economics of biofuel production and the alcoholic beverage industry.
“Has been used”. Not just talked up.
So you can make a film in a DVD burner, and shove pure water out one side leaving ethanol on the other. (One presumes some kind of pre-filtering to remove solids and maybe even a rough fast low concentration distillation to leave other contaminants behind.)
Fresh water is nice, but a new way to make pure booze cheap? Very nice ;-)
That you can do it in a DVD burner and make supercapacitors with 1/2 the power density of Li batteries in the process? Priceless.
Oh, and the wiki also points out IBM has made a variety of electronic parts out of it including junctions and transistors and even LEDs and logic circuits. All carbon.
Graphene has the ideal properties to be an excellent component of integrated circuits. Graphene has a high carrier mobility, as well as low noise, allowing it to be used as the channel in a field-effect transistor. The issue is that single sheets of graphene are hard to produce, and even harder to make on top of an appropriate substrate. Researchers are looking into methods of transferring single graphene sheets from their source of origin (mechanical exfoliation on SiO2 / Si or thermal graphitization of a SiC surface) onto a target substrate of interest. In 2008, the smallest transistor so far, one atom thick, 10 atoms wide was made of graphene. IBM announced in December 2008 that they fabricated and characterized graphene transistors operating at GHz frequencies. In May 2009, an n-type transistor was announced meaning that both n and p-type transistors have now been created with graphene. A functional graphene integrated circuit was also demonstrated – a complementary inverter consisting of one p- and one n-type graphene transistor. However, this inverter also suffered from a very low voltage gain.
According to a January 2010 report, graphene was epitaxially grown on SiC in a quantity and with quality suitable for mass production of integrated circuits. At high temperatures, the Quantum Hall effect could be measured in these samples. See also the 2010 work by IBM in the transistor section above in which ‘processors’ of fast transistors on 2-inch (51 mm) graphene sheets were made.
Well, if you can make it in a DVD burner, with a laser, I have to think that a single layer of starting material can be deposited and lased… This is starting to look like seriously interesting stuff. I note in passing that it has “Quantum Hall Effects”… so my assertion that we’re getting down to the area where QM effects start to show up also is looking justified…
Graphene’s high electrical conductivity and high optical transparency make it a candidate for transparent conducting electrodes, required for such applications as touchscreens, liquid crystal displays, organic photovoltaic cells, and organic light-emitting diodes. In particular, graphene’s mechanical strength and flexibility are advantageous compared to indium tin oxide, which is brittle, and graphene films may be deposited from solution over large areas.
So you can make a PN junction (needed for a solar cell) and transparent electrodes, along with a very tough substrate. Now that’s a solar cell I could like.
The USC Viterbi School of Engineering lab reported the large scale production of highly transparent graphene films by chemical vapor deposition in 2008. In this process, researchers create ultra-thin graphene sheets by first depositing carbon atoms in the form of graphene films on a nickel plate from methane gas. Then they lay down a protective layer of thermoplastic over the graphene layer and dissolve the nickel underneath in an acid bath. In the final step they attach the plastic-protected graphene to a very flexible polymer sheet, which can then be incorporated into an OPV cell (graphene photovoltaics). Graphene/polymer sheets have been produced that range in size up to 150 square centimeters and can be used to create dense arrays of flexible OPV cells. It may eventually be possible to run printing presses laying extensive areas covered with inexpensive solar cells, much like newspaper presses print newspapers (roll-to-roll).
While silicon has long been the standard for commercial solar cells, new research from the Institute of Photonic Sciences (ICFO) in Spain has shown that graphene could prove far more efficient when it comes to transforming light into energy. The study found that unlike silicon, which generates only one current-driving electron for each photon it absorbs, graphene can produce multiple electrons. Solar cells made with graphene could offer 60% solar cell efficiency – double the widely-regarded maximum efficiency of silicon cells.
It looks like folks are figuring out how to make this stuff relatively cheaply and in volume. It has some very interesting properties, including strength:
Graphene paper or GP has recently been developed by a research department from the University of Technology Sydney by Guoxiu Wang, that can be processed, reshaped and reformed from its original raw material state. Researchers have successfully milled the raw graphite by purifying and filtering it with chemicals to reshape and reform it into nano-structured configurations, which are then processed into sheets as thin as paper, according to a university statement. Lead researcher Ali Reza Ranjbartoreh said: ‘Not only is it lighter, stronger, harder and more flexible than steel, it is also a recyclable and sustainably manufacturable product that is eco-friendly and cost effective in its use.’
All that, and it can be used to pour a neat Vodka too?
What’s not to like?