Print 27 comment(s) - last by Jedi2155.. on Jun 15 at 8:35 AM

New nanotech-based filtration could save buckets of energy.

Seawater desalination is no easy task. Traditionally, vacuum distillation techniques have been used, and this process requires a great deal of energy. More recently, reverse osmosis facilities have come online. These facilities use a special permeable membrane to separate salts and minerals from liquid water. As of January, there are more than 13,000 desalination plants pumping out over 12 billion gallons of water a day.

While cogeneration facilities have helped to cut down the cost of vacuum distillation and reverse osmosis plants are marginally more efficient in terms of energy used, work in the unrelated field of biology and molecular transport systems may promise an even better type of filtering membrane for osmosis systems.

Researchers at the Lawrence Livermore National Laboratory, while studying the process of molecular transportation across cell membranes, have come up with a new type of filter. The filter mimics the properties of cell membranes and is especially efficient in the transport and filtration of water molecules. Their work is based on -- you guessed it -- carbon nanotubes.

What makes these CNT-based filters so efficient is their hydrophobic properties, or the way they repel water molecules. Water moves through the CNT channels in a membrane much more quickly than in conventional filters because the molecules do not stick to the sides of CNTs. Instead, they stream through them unhindered, like a bullet train.

After this discovery, the researchers tested their artificial membrane for desalination efficiency. They found that the 1.6nm diameter tubes successfully prevented the ions that make up salts from traversing while letting the water molecules flow freely. The mechanism for this selectiveness lies in the small diameter of the channel along with the charge held at the end of the nanotubes.

Aleksander Noy, a senior member of the LLNL research team explains, “while carbon nanotube membranes can achieve similar rejection as membranes with similarly sized pores, they will provide considerably higher permeability, which makes them potentially much more efficient than the current generation of membranes.”

While the LLNL findings promise a great deal for desalination and other processes where similar filtering is used, some refinement will still be required. The ability to construct membranes of different materials and control the charge and diameter of the nanotube pores will weigh heavily into their efficiency and usefulness in different applications.

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RE: Great!
By masher2 on 6/10/2008 10:04:06 AM , Rating: 5
> "Beacause carbon nanotubes are acutally carcinogenic (similar to asbestos)."

We have no idea if CNTs are carcinogenic or not; their similarity of asbestos fibers has led some to hypothesis they may be. However, even if so, an extremely low concentration of CNTs ingested in water is unlikely to cause the same sort of damage that inhalation of large quantities does to the lungs.

RE: Great!
By TheSpaniard on 6/10/2008 10:09:13 AM , Rating: 2
actually... CNTs are carcinogenic, its been shown to congregate in the lungs, due to its size, if allowed to flow freely in the blood stream, causing damage similar to asbestos.

you are right thoughthe quantitys injested would be negligable, but I expect an over-reaction anyway

RE: Great!
By masher2 on 6/10/2008 10:40:08 AM , Rating: 2
> "its been shown to congregate in the lungs...causing damage similar to asbestos"

It's been shown to cause inflammatory effects similar to asbestos. While it's a reasonable assumption to link that to carcinogenesis, the fact remains that no research has yet verified this.

RE: Great!
By TheSpaniard on 6/10/2008 11:08:14 AM , Rating: 3
fair enough, there is no reasearch that has qualified CNTs to go on the list of known carcinogens.

the "inflammatory effects" are caused by damage done to the cells in the area --> cells must divide to replace damaged cells --> cancer risk. thats what I was pointing out. now, how much is required to cause these responses was left unclear in the papers I've read, as the papers were focused on CNTs curing cancer, not casuing it.

I wish I had access to pubmed right now so I could show the paper

RE: Great!
By Treckin on 6/10/2008 5:02:39 PM , Rating: 2
AFAIK cells divide tens of thousands of times every day. I have stitches in my arm right now; am I at a greater risk for cancer because my cells are dividing to heal?

RE: Great!
By TheSpaniard on 6/10/2008 5:12:18 PM , Rating: 2
BACTERIA divide tens of thousands of times every day. your cells do not.

the only cells that do that in the human body are blood cells. STEM cells having to divide into 2 stem cells instead of stem and terminal cell is actually lowers the cells ability to retain genome integrity.

so yes you are at an increased risk of cancer.

There are two ways to "induce" cancer either killing off a lot of cells, which can leads to the second, and large scale gene damage

now the only reason your arm is not in any serious danger is because the trauma is over, CNTs stuck in your lungs don't go away and therefore repeatedly do damage to the same area.

RE: Great!
By LivingDedBoy on 6/10/2008 5:37:21 PM , Rating: 1
Everything causes cancer these days, so yeah, stop whining about it? Maybe?

If you worried about everything that 'increases risk of cancer' then I'm willing to bet you wouldn't be sitting in front of your computer because the EMF from your monitor could cause cancer. As could florescent lighting that more than likely surrounds the majority of us day to day, and cell-phone undoubtedly in their pockets. Every day there is another study that correlates some other thing to increasing the risk of/causing cancer.

As someone who has had his mother diagnosed with cancer, I still could care less as to what might cause it. I'd rather them focus on studies on how to cure it.

RE: Great!
By TheSpaniard on 6/10/2008 7:01:08 PM , Rating: 2
umm... cell phone wavelengths and other electronic devices have far lower energy than is required to do any real damage to your cells or DNA. that is in your basic biology textbook!

consult "the biology of CANCER" by Robert A Weinberg

RE: Great!
By LivingDedBoy on 6/11/2008 12:50:44 PM , Rating: 2
Ahh but they do emit EMF, meaning it will increase the risk of cancer, regardless of how much energy it takes to effectively damage DNA.

Anything that puts out any kind of radiation can increase your risk. Even if it is .000000001% its still an increase over someone who does not expose themselves to said radiation.

I'm just saying that everything can increase your risk of cancer. If you take the time to look around and do some research I'm sure you can find some study or another that relates any givin thing to increasing the risk of cancer. All in all I could really give less of a crap if these can increase the risk, so could anything else for that matter.

If these carbon nanotubes can filter out any givin chemical from water, meaning less disease in general, more usable materials etc. I'm not gonna cry about an increased risk of cancer since there is already so much out there that can do the same.

RE: Great!
By Jedi2155 on 6/10/2008 9:01:33 PM , Rating: 2
It is also shown that the EM radiation from CRT's are less than that of Fluorescent lights

RE: Great!
By TheSpaniard on 6/10/2008 10:01:55 PM , Rating: 2
that link you provided has a very good graph that shows "harmful" radiation, they call it ionizing but I prefer to think of it as "can damage DNA", and things radiation that really does not have the energy to do much of anything to biomolecules

RE: Great!
By Jedi2155 on 6/15/2008 8:35:43 AM , Rating: 2
I also have another article in a IEEE spectrum magazine laying around that studies the effects of ionizing radiation emitted from mobile devices such as cell phones etc. to be of such insignificant value relative to the many other things we encounter in life. It is pretty insignificant and I feel safe around most forms of EM radiation. Although a EM Pulse to level a nuke would form still scares me :).

RE: Great!
By masher2 on 6/10/2008 8:53:41 PM , Rating: 2
> "BACTERIA divide tens of thousands of times every day. your cells do not."

As far as I know, not even the fastest growing bacteria are this fast...a hundred times a day is about the limit.

RE: Great!
By TheSpaniard on 6/10/2008 9:58:29 PM , Rating: 2
yea its only something like 20 minutes per division...

I think he meant create tens of thousands?

RE: Great!
By TheSpaniard on 6/10/2008 10:04:09 PM , Rating: 2
darn you edit button!!!! (lack there of)

the comment was meant as a witty response to say that bacteria divide a lot but the cells in your body do not

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