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Earth Science Technology

Researchers Discover Efficient Way To Filter Salt, Metal Ions From Water (phys.org) 67

schwit1 shares a report on a new study, published in Sciences Advances, that offers a new solution to providing clean drinking water for billions of people worldwide: It all comes down to metal-organic frameworks (MOFs), an amazing next generation material that have the largest internal surface area of any known substance. The sponge like crystals can be used to capture, store and release chemical compounds. In this case, the salt and ions in sea water. Dr Huacheng Zhang, Professor Huanting Wang and Associate Professor Zhe Liu and their team in the Faculty of Engineering at Monash University in Melbourne, Australia, in collaboration with Dr Anita Hill of CSIRO and Professor Benny Freeman of the McKetta Department of Chemical Engineering at The University of Texas at Austin, have recently discovered that MOF membranes can mimic the filtering function, or "ion selectivity," of organic cell membranes. With further development, these membranes have significant potential to perform the dual functions of removing salts from seawater and separating metal ions in a highly efficient and cost effective manner, offering a revolutionary new technological approach for the water and mining industries. Currently, reverse osmosis membranes are responsible for more than half of the world's desalination capacity, and the last stage of most water treatment processes, yet these membranes have room for improvement by a factor of 2 to 3 in energy consumption. They do not operate on the principles of dehydration of ions, or selective ion transport in biological channels.
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Researchers Discover Efficient Way To Filter Salt, Metal Ions From Water

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  • ... combating water desertification in Cape Town.

    • Hooray, Sponge Bob

  • by rsilvergun ( 571051 ) on Sunday February 11, 2018 @12:36AM (#56102837)
    There's a huge benefit to be had from scarce water. Here in the states we've already got some of our oligarchs moving to take control of the water supply and spending a lot of money to do it. If we were smart we'd make it a point to prevent anyone from profiting from access to clean water. Once somebody can make money off a resource they generally want the value of that resource to go up. And scarcity's an easy way to make it happen.
    • There's a huge benefit to be had from scarce water.

      I think you have the definition of benefit backwards.

      • by rtb61 ( 674572 ) on Sunday February 11, 2018 @01:36AM (#56102947) Homepage

        It was a simple deduction based upon greed and logic. Basically pretty accurate but it is not about water, that is an incomplete lie, far more accurately it is about cheap water. The psychopathic corporations want to suck up all the cheap water they can at the lowest price possible for manufacture and industrial agriculture and then charge us enormousness amounts of money for way more expensive water ie they user river water, pollute it and dump it back into the environment making it unsuitable for use downstream and then charge us for very expensive desalinated water.

        Now the biggest cost in water in getting it from where it is, to where you need it, so cheap upriver to downhill use via gravity, cheapest, that's for psychopathically greedy corporate use. For us chumps pump it up from sea level to us hundreds of feet above sea level and that is expensive now add in desalination via reverse osmosis and the efficiency they are talking about is having to pump much more saltwater to draw out the fresh water, like 5 times as much.

        So getting greater efficiency is worthwhile. So for example having a nuclear plant close to a desalination plant. The nuclear plant can use the waste water from the desalination plant, so you recover the energy that the nuclear plant would otherwise us to pump water. You could also put the desalination plant below sea level and use tidal forces for flow and then only pump fresh water to hundreds of feet above sea level. Think of a supported concrete hemisphere, with the membrane across the bottom and a pump at the top drawing off fresh water and the tide shifting water past the base of the hemisphere. So high capital cost but energy inputs are for shifting fresh water and efficiency of the membrane is not that critical as the tide will shift massive volumes past the filter (not necessarily a hemisphere but you get the idea, say strings of box culverts but the idea remains the same, smart move make them artificial reefs and you get a fisheries bonus, maybe even wind farm fitted to the system, you have the structure so why not, concrete culverts and concrete footings into the sea bed). Done really well, the system could be extremely productive, with no energy input after construction, in fact energy surplus for the right location.

        • by Applehu Akbar ( 2968043 ) on Sunday February 11, 2018 @09:42AM (#56103721)

          If the 14 million people of greater Los Angeles could desalinate their own water, the city would no longer have to suck it up from as far away as Wyoming. This would mean that water-short inland areas could keep more of their own supply.

          Because the primary customer for desalination in this region is California, they are not going to consider nuclear as the energy supply - that's Arizona's job. Fortunately, desalination processes not requiring heat can tolerate fluctuating energy sources, which would make it a good use for those California windfields.

        • far more accurately it is about cheap water.

          Too bad potable water doesn't grow on trees [instructables.com]. Or fall from the sky.

          The problems with potable water are entirely self-made. People want to live where there isn't enough, or political borders prevent people from moving away from areas where there isn't enough to areas where there is enough. Anyone or any corporation exploiting lack of cheap water can only do it because of these two things.

          So for example having a nuclear plant close to a desalination plant. The

        • Better to move to where there is an abundance of snow in winter and rain in summer,

    • If we were smart we'd make it a point to prevent anyone from profiting from access to clean water.

      That would actually be a very not smart thing to do.

      Tell me something, why hasn't anyone landed on the moon in decades? I'll tell you why. Because we know it can be done and there is no profit in it. There's two surefire ways to get someone to do something for you, tell them it can't be done or tell them they can make a lot of money doing it. If you want something done cheaply then you get many people trying to make that money and the one that figures out how to do it best makes the most money.

      Why is th

      • Profit motives can be effective, but it's important to understand that they will optimize towards profit, not accomplishing the stated goal. The profit motive is responsible for why bottled water manufacturers are able to cut their own production costs. The solution to the problem of clean water availability is a matter of building infrastructure, and of inventing technology to improve efficiency/output/etc.. The former basically boils down to proper public funding, and the latter is mostly coming from u
      • by Teun ( 17872 )
        For measures of 'anyone'.
        There is profit for giving the general population and also industry access to clean water (and air for that matter).
        It is society as a whole that profits and you are part of that society.

        In other words, it is not beneficial to have individual investors get the profits, for best return on investment this needs to be a public utility based on a strong and fair legal system.
        Which for the moment will leave large swaths of the USofA dry...
      • > > a point to prevent anyone from profiting from access to clean water.

        I think the point is to prevent people from using underhanded ways of screwing with something already good for the sake of profit.

        Unfortunately, access to things already good is getting scarcer. Oh, it sucks to be a selfish little shit.

      • Around here we have a saying that water flows uphill towards money.

    • by PPH ( 736903 )

      some of our oligarchs moving to take control of the water supply

      Those oligarchs aren't always private parties. We recently went through a bit of resource grab by the local government here in Washington State. The city water department supported an 'environmental' suit against rural property owners, effectively stopping them from drilling wells or drawing from bodies of water. And that stalled building permits. But .... the city stepped in and offered to build their utility system out. And sell these rural homes water. For a few hundred dollars a month plus $50K to $75K

  • by Enigma2175 ( 179646 ) on Sunday February 11, 2018 @12:42AM (#56102857) Homepage Journal

    Wow, with this technology they would be able to produce enough salt to last them forever!

    • by Dantoo ( 176555 )

      Yeah,,,Until "Big Salt" buys up all the patents and forces us to keep production low. We'll be scraping the lamps in cheap hotel rooms for decades yet.

    • Wow, with this technology they would be able to produce enough salt to last them forever!

      Folks in South East Asia like to season their food with plenty of salty soy sauce and putrid dead fish sauce. So I see no need for them for desalinated water.

      Just pump soy and fishy tasting sea water directly into the taps at home, and market the water as "pre seasoned". No-one drinks tap water these days anyway. All other uses for water like cooking, bathing and washing can be done with fishy soy sauce water.

  • Uranium (Score:4, Interesting)

    by blindseer ( 891256 ) <blindseer@@@earthlink...net> on Sunday February 11, 2018 @01:08AM (#56102897)

    What kinds of ions can they filter out besides lithium? Japan is so desperate for energy that they've been researching a way to filter uranium from ocean water for a very long time now. They've had some success but so far it's just cheaper to buy uranium from Australia, which oddly mines a lot of uranium but does not use it for energy in their own country.

    There's a lot of uranium in the ocean. More than we could ever use. Nuclear power may not be "renewable" like wind and sun but it is just as "sustainable". There is so much uranium on the planet that the sun would go red giant and boil away the oceans before we run out of uranium. Being able to filter it from the ocean means no one could claim a monopoly on mining it. Oh, and no one should run out of fresh water ever again either.

    • by kobaz ( 107760 )

      What's your source?

      • Re:Uranium (Score:4, Informative)

        by blindseer ( 891256 ) <blindseer@@@earthlink...net> on Sunday February 11, 2018 @02:08AM (#56102999)

        Seriously? Go to Wikipedia and search for "uranium". Since that seems too difficult for you here's a link and a quote.
        https://en.wikipedia.org/wiki/... [wikipedia.org]

        An additional 4.6 billion tonnes of uranium are estimated to be in sea water (Japanese scientists in the 1980s showed that extraction of uranium from sea water using ion exchangers was technically feasible).

        And don't just reply with, "Wikipedia is not a valid source!" Follow the citations on the Wikipedia page and you'll find this:
        http://www.jaea.go.jp/jaeri/en... [jaea.go.jp]

        I'm sure that there are better sources out there but you can type into Google just as easily as I can.

      • Re: (Score:2, Funny)

        by Anonymous Coward

        The ocean. Weren't you listening?

    • Re:Uranium (Score:4, Interesting)

      by serviscope_minor ( 664417 ) on Sunday February 11, 2018 @07:00AM (#56103467) Journal

      They've had some success but so far it's just cheaper to buy uranium from Australia, which oddly mines a lot of uranium but does not use it for energy in their own country.

      I don't think it's especially odd. Nuclear energy is a bit of a pain in the arse for a variety of reasons. Australia has vast land area (so large natural resources) and few people, so there's no point in going for any even slightly difficult option.

    • Well, well, apparently the uranium leaches from rocks in the ocean.

      Suggestion: go get the rocks. The stuff in the water is chicken feed.

  • by 140Mandak262Jamuna ( 970587 ) on Sunday February 11, 2018 @12:21PM (#56104203) Journal
    Energy is just one of the cost in de salination. Cost of these membranes themselves are pretty high. So even at a higher energy efficiency, the cost per gallon of fresh water might not drop.

    Already the Sun heats the oceans and puts so much of moisture in the atmosphere. At least on coastal areas in the tropics, wringing the air dry and squeezing moisture out might be competitive for drinking water. US Military developed these machines that can make water from dry desert air. Now I see these machines showing up for civilian use at civilian prices in India. A 900 USD version making a few dozen gallons for small schools and a 90$ version making a couple of gallons a day for homes.

    It is pretty damned humid there and the dew point is just a few degrees below air temperature. Cooling the air by a few degrees is enough to condense the moisture.

    • Have you seen the air pollution in New Dehli? I for one wouldn't want to drink it

      • by Luckyo ( 1726890 )

        Something most people forget is that things that are harmful to ingest in lungs are often harmless in stomach and vice versa. That's why you make sure you lift the head back before you breathe into the mouth for CPR administration. If you breathe air into the stomach, patient's stomach will evacuate itself as a reflex to air entering stomach. Evacuated material in unconscious person is likely to enter the lungs, causing severe damage.

      • Who asked you to drink it? As a visiting alien you would buy bottled water. Its for the locals. They already breath the air and they would be no worse off to drink water wrung out of that air. The alternative is even more highly polluted water.

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