This looks to be a good try although I am not terribly optimistic.
Free salt ions will coagulate and easily block up the filter. The
trick we were attempting to commercialize in 2000 was to induce that
effect in a tank and use gravity to induce full separation. It means
putting a small amount of energy back into the system and was proven
possible in a tube.
It may actually work to have two closely spaced filters oppositely
charged so that the salt is pushed away. Water will still find its
way through to the oppositely charged filter.
Of way more importance is that it is becoming technically possible to
produce a nice large sheet of graphene. This opens up the whole
spectrum of application.
Hopefully when we establish full tooth restoration, it will include a
surface layer of graphene to make it impervious to stress.
Using Graphene,
Lockheed Martin Wants To Turn Salt Water Into Drinking Water
A new Lockheed Martin
project promises to cheaply and easily turn seawater into drinking
water.
By Kelsey D.
AthertonPosted 03.18.2013
It's surprisingly hard
to find safe drinking water on Earth--this on a planet covered in
water. A new project by Lockheed Martin hopes to change
that, and do it cheaply. Using a graphene filter, Lockheed hopes to
transform salt water into drinking water by the end of the year.
The timing couldn't be
better. Ending water scarcity is one of the United
Nations's millenium development goals. But it is a daunting task:
while there’s enough freshwater for everyone on earth, it isn’t
very evenly distributed, and untangling that distribution is a
Herculean feat. For the44 percent of the world’s population
that lives within a hundred miles of coasts, technology that can
convert salt water into fresh water is an important alternative.
Desalination--that
process of removing salt from water to make it drinkable--has been
used forthousands of years. One problem: Removing salt from
seawater is less efficient than starting from freshwater, and
significantly more expensive. When a country relies on
desalination to get most of its water, it’s usually because it
has a tremendous amount of oil money and no other good options. Costs
are coming down, but gradually, and major desalination attempts
remain prohibitively costly for much of the world. One of the grander
attempts in recent history is theBeijiang Power and Desalination
Plant, which has a price tag of $4.1 billion.
Ancient methods of
desalination involved crude filters and capturing steam from boiling
water, a practice which today has been improved on an industrial
scale. But, again, the energy costs are enormous--it's one thing for
ancient sailors to boil water on a ship at sea to get them through
the day, it's another thing entirely to provide for the daily water
needs of hundreds of thousands of city-dwelling people. Some
desalination plants still start by boiling saltwater in a large
chamber. Once that steam has lifted away from the salt, it is cooled
at the top of the chamber and condenses, draining out into tanks for
further filtration. Energy is required to both boil and cool the same
water, making the whole process pretty inefficient. An alternative
and more popular method for large-scale operations is reverse
osmosis. In reverse osmosis, water is sent through filter after
filter after filter at high pressure, hoping to remove more and more
salt each time. Getting water through these filters is the most
energy-intensive part of the process, and the thinner the filter, the
less pressure you need.
Lockheed’s proposed
desalination project filters through graphene, a material
already touted as a modern marvel. A thousand times stronger than
steel, it's also just one atom thick. Last July, Popular Science
covered its potential use in water filtration. Passing seawater
over tiny pores, just one nanometer wide, the filter will let water
molecules through, while blocking out the atoms that make salt. These
filters are a much less energy-intensive option, and much better at
filtration. Lockheed expects to have a prototype filter
available by the end of 2013.
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