A World of Fresh, Clean Water for the Taking

A new device out of MIT is aimed at making efficient desalinating devices cheap, portable, and battery-powered. Current desalination mechanisms are extremely expensive energy hogs. But the MIT device gets down to the molecular level to sort the water from the salt molecules. Using smarter nanotechnology, the job can be done better.

We are using a phenomenon called ion concentration polarisation to "push" the salt out of seawater,' says Jongyoon Han, who led the research at Massachusetts Institute of Technology. 'When a voltage is applied across a small membrane made from an ion-selective material such as Nafion, something unusual happens. On one side of the membrane, charged particles are repelled - and on the other side, they are collected.'

Han's team developed a microchip-sized device that funnels a stream of water down to a fork and splits into two channels. The entrance to one channel is covered with a charged Nafion membrane, which shields the water flowing down it and pushes any salt down the other channel. Crucially, the shield also repels other charged particles, both positive and negative, which includes most organic matter and microorganisms, such as bacteria, viruses and other contaminants.

But to function effectively the process requires very small water channels and these can only produce tiny amounts of water on their own. 'Our future direction is similar to how the semiconductor industry makes microchips,' Han explains. 'We can envision thousands of water channels on a single chip - the goal is to make systems that can produce around a litre of purified water over ten minutes.'

Although Han admits this is a relatively small amount, it may be possible to run the device continually for a long time using solar power, which could be extremely valuable in areas of critical water shortage. _ChemistryWorld

Battery or solar powered portable desalination / water purification devices would be the perfect survival method of assuring clean water supplies wherever there is water of any kind. Pre-filters would be needed to elminate larger particles that would clog the micro-channel intakes, but such pre-filters are cheap and easily made from ordinary materials.

It will take some work to bring the manufacture of such devices up to scale, and to make them re-usable over a long time span. But that is why US taxpayers allow their governments to cut them to the quick -- to pay for world-leading research in virtually every area of science, biomedicine, and technology (among other things).

You may as well bask in all of this great science and technology while you can. Soon the US government will be diverting ever larger portions of its budget away from r&d and toward vast new exponentially growing entitlements + the rapidly growing interest on the federal debt.