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

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.

Comments

Good news for ...

[CaptainDork]

... combating water desertification in Cape Town.

Re:Good news for ...

[PingPongBoy]

Hooray, Sponge Bob

Re:Good news for ...

[Anonymous Coward]

Yes, can I buy none please. Ohhh, works only in lab, maybe available in 2040.

The problem with water is political

[rsilvergun]

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.

Re:The problem with water is political

[omnichad]

There's a huge benefit to be had from scarce water.

I think you have the definition of benefit backwards.

Re:The problem with water is political

[rtb61]

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.

Re:The problem with water is political

[Anonymous Coward]

Why not use a tidal, wind or solar plant next to a desalination plant since all of these can be built on water?

Re:The problem with water is political

[blindseer]

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 the fastest car in the solar system a Tesla Roadster on a collision course with Mars? Because someone said it couldn't be done. You want to see someone try again? Show that there is money to be made shooting rockets at Mars. Same goes for cheap and clean water. We already know clean water can be made. The trick is to get it cheap, that means creating a profit motive to do it and having people compete for that profit.

Re: The problem with water is political

[Anonymous Coward]

If we all have wells with infinite clean water, they are essentially worthless in a market.
If everyone else's gets "accidentally" contaminated, mine is infinitely valuable in the market.

Re:The problem with water is political

[Anonymous Coward]

I want to tell you that there is no way you can not profit by sending a spaceship to Mars. Will someone then do it in a non-profit manner because it can't be done?

Re:The problem with water is political

[king neckbeard]

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 university research. So, profit motives don't currently seem to have much in line with useful water processing and distribution.

Re:The problem with water is political

[Teun]

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...

Re:The problem with water is political

[PingPongBoy]

> > 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.

Re:The problem with water is political

[Applehu Akbar]

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.

Re:The problem with water is political

[Applehu Akbar]

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

Re: The problem with water is political

[Anonymous Coward]

What about food then? Shouldnt that be also free from the profit motive, as âaccess to foodâ is probably the second most urgent necessity for survival? We could say that due to profit motive people counterfeit food; they sell anything as coffee, they sell horse meat as mutton or beef and they sell even melamine as milk. Wouldnt we be better off without the greed of individual actors (including individuals greedily having salaries) in the food industry?

And the list goes on and on: if people could profit by selling human organs, there would be no doubt at least attempts of selling organs of nonconsenting people involved.

Then again: IMO smart people would favour individual rights and economic freedom and have the government chase the criminals, not micro or macromanage economics. The crony-corporatism as most people see today, should be understood as the creation of the macro level failure of current economic theories of money, interest and unemployment...

Re:The problem with water is political

[Anonymous Coward]

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.

Dude, you should really take an economics class.

Re:The problem with water is political

[PPH]

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 assessments for the pipeline construction. Funny thing: They take the city water out of the same watershed that the landowners were planning to use. So gallon for gallon, water consumption from the watershed would have been the same.

But here's the thing: If a private company (the oligarch) were to try this stunt, they'd have been run out of the state. When a government does it through a phony environmental group, there is no down side for them. Fortunately, the state legislature saw through the suit and changed the law. While the city officials will go on as though nothing happened, FOIA requests are beginning to reveal their connections to the NGOs and their employees are packing their bags pretty fast right now.

Re:The problem with water is political

[Solandri]

far more accurately it is about cheap water.

Too bad potable water doesn't grow on trees. 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 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 have that backwards. You can use the waste heat from the nuclear plant (about 2/3 of the energy it produces) to drive thermal evaporative desalination at a lower electrical cost than reverse osmosis. Unfortunately people have this irrational hangup over the word "nuclear" and don't want to drink water desalinated via heat from a nuclear plant, even if it's less radioactive than natural fresh water sources. So we needlessly throw away 2/3 of the energy our nuclear and fossil fuel plants generate in the form of waste heat.

Re:The problem with water is political

[lsatenstein]

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

Re:The problem with water is political

[Anonymous Coward]

You can do thermal desalination, but the osmotic pressure of water decreases up to about 40C so reverse osmosis becomes more energy efficient if you use the warm outfall of the reactor.

You're already pumping huge volumes of salt water to cool the reactor, so just snaffle some of the outfall into your reverse osmosis plant and incorporate the brine output back into the reactor outfall.

Modern sea water reverse osmosis desalination plants use less than 3.5kWh to produce a cubic metre of fresh water.

Top Secret

[Enigma2175]

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

Re:Top Secret

[Dantoo]

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.

Re:Top Secret

[PolygamousRanchKid]

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.

Color me skeptical

[Anonymous Coward]

Because forward osmosis 6 years ago was supposed to be the new technology to save us all.

The problem with water is dirt.

[Anonymous Coward]

Cart before horse. Clean water already is scarce. Dirty water is plentiful. Guess who wants to be at the head of the former? Everyone.

Uranium

[blindseer]

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.

Re:Uranium

[kobaz]

What's your source?

Re:Uranium

[blindseer]

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/...

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...

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

Re:Uranium

[Anonymous Coward]

The ocean. Weren't you listening?

Re:Uranium

[Anonymous Coward]

Except nobody wants nuclear power next door, and no ammount of ranting from its fans will change that. They dont believe it is safe, and nobody trusts scientists anymore due to the actions of the denialist shills. Hows it feel to be bitten on the ass by your own bullshit?

Re:Uranium

[Anonymous Coward]

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.

This sort of argument typically assumes constant use increase, when the evidence suggests that our energy use typically increases exponentially, in part caused by available of cheap energy. To that last bit, availability of cheap energy drives use of even more energy. In the US, suburbs are a thing because cheap petrol for your petrol guzzling car. (Go look what it'd cost to run that same car over in Europe.) To the first, even a seemingly constant increase of energy use of, say, 7% year on year, means we double our energy use every ten or so years. And moreover, it means that in the last doubling period, here ten years, we've used as much energy as in all of history leading up to this point.

With that in mind, I don't know how much uranium is in the oceans, but I'm fairly confident that given enough energy use growth we can deplete it well before the sun takes us with it in its grave. All it takes is a high enough growth rate.

Oh, and then there's the minor problem of not actually being able to extract that uranium from the ocean in any sort of cost-effective manner, yet, if ever.

Re:Uranium

[Anonymous Coward]

Of course, there's technically feasible, and then there is energetically reasonable. Unless there is a positive EROEI (Energy Return On Energy Invested), then there is little point in doing it. Improved technology in various areas might make that likely. However, with the increased use of renewables, it might be not unreasonable to run a process with a moderately negative return, as it could be considered a form of storage of temporarily excess renewable energy. That's not the total cost of energy for refuelling of a nuclear plant, but a good chunk of it, I would imagine.

One of the concerns with nuclear power is that if expanded then ores of poorer quality might lead to negative EROEI, although power generated might still have utility, as it would be fairly dependable. It may well be simpler, from a process consideration, to use renewables to power recovery from sea water, at an energy loss, than try to power mining, even at a small energy gain, as you could envisage an extraction plant placed near a large offshore wind farm, whereas uranium ore reserves might not even be in the same country.

Re:Uranium

[FormOfActionBanana]

https://en.wikipedia.org/wiki/...

Re:Uranium

[serviscope_minor]

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.

Re:Uranium

[PingPongBoy]

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

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

Re:Uranium

[Applehu Akbar]

Hows it feel to be bitten on the ass by your own bullshit?

This applies to the leftists who won't stop ranting that the most important and ultimate problem facing mankind is carbon. Suddenly, they are starting to realize that the only feasible way to get rid of fossil fuel usage is to replace it with nuclear. Their mirrors and pinwheels can never be more than part of the solution.

Re: Uranium

[Anonymous Coward]

The energy costs the same, the oligarchs wont let poor people own cars.

Re:Uranium

[Anonymous Coward]

Dear blindseer: The article you quote says that we currently have 4.6 billion tonnes and
  using approximately 70k tonnes per year. So, we run out after 65k years even at the
current rate of consumption.

Last time I checked, the sun was going to develop into a read giant no sooner than ca. 500 million years into the future.

You can quote whatever you want, but you should check whether your calculations aren't off by several orders of magnitude before making any bold claims.

Re:Uranium

[PPH]

Umm. The fans wouldn't mind it next door. The rest of you can just turn off your air conditioning.

Re:Uranium

[Anonymous Coward]

I was doing exactly that The only problem is that google pointed me to a loud mouth braggart on a public bulletin board called. Slashdot.org.

Thanks for messing up the google results. You are a real jerk.

Re:Uranium

[blindseer]

That's 4.6 billion tons of uranium in the ocean IN ADDITION to the uranium we can mine on land. That might not seem like much in the grander scheme of things but if we can figure out how to economically extract uranium from ocean water then for the next 60k years no one will be without energy or clean water. That's a long time to do things like figure out how to get uranium from lesser sources on this planet, explore other planets for resources, or develop fusion power.

What of people without access to the sea? There is enough uranium in the dirt in most anywhere on the surface of this planet to get enough uranium to last effectively forever, it's everywhere. Also everywhere is the air, and even in the driest desert it has water vapor in it. With nuclear technology no one would be lacking energy or water. If you have energy and clean water then that makes getting things like food, shelter, and clothing near trivial.

Re:Uranium

[blindseer]

It might in the future, with future tech

You mean like a future technology that can extract uranium from sea water? That's kind of the point, it looks like we might have that technology now.

solar power are only getting more competitive in the meantime.

Nuclear power isn't standing still. This is a moving target and nuclear power is so far ahead that it produces 20% of the electricity in the USA while solar produces maybe 1%. I think it would be delusional to think that there is going to be some great leap in solar power that would allow it to eclipse nuclear any time soon. Maybe it can in 50 years but for the next decade we will need something and that something is nuclear power.

It just seems so odd to place such faith in the future development in solar power to displace all others based on the predictions of solar energy development, while at the same time believe that future development in other technologies (like nuclear) will essentially stand still. It's quite possible solar will win out eventually but that didn't happen yet. Even with modest advancements in nuclear power technology we can double the energy we can get from nuclear power. That means taking even the pessimistic estimate of uranium reserves of 5 years and turning that into 10. We could see this leap in solar technology in 10 years. That means that we'd have cheap and plentiful nuclear energy for a decade as we figure out how to get solar to replace it. If solar power does not replace nuclear then we'd still have 10 years on finding more uranium, or developing fusion energy, or whatever.

I agree that solar power technology is improving. If you cannot see that nuclear power is also improving then you've been looking at the sun for too long.

Re:Uranium

[Anonymous Coward]

Just because there are 4.6 billion tons in the ocean, doesn't mean you can extract that.

For one, as you extract, the concentration in water will fall. Even if you can always extract a uranium atom from 1L of water, there has to be one in it.

Secondly, not all water in the oceans cycles through to locations you may have extraction locations. E.g. deep ocean water turns over only slowly, and currents are a factor.

Also it's much more useful to talk about how long you expect a resource to last given expected demand. If you feel that nuclear power needs to expand 100 times, then that's 650 years, and if only 20% is extractable due to currents and concentrations, that's only 130 years. So these balances are important.

Re:Uranium

[Anonymous Coward]

This applies to the leftists who won't stop ranting that the most important and ultimate problem facing mankind is carbon. Suddenly, they are starting to realize that the only feasible way to get rid of fossil fuel usage is to replace it with nuclear.

Shees, can't we have one single /. article without the Nuclear Zealots peddling their wares? Yes, we know by now about your delusions, but sorry, Nuclear is still a bad idea, at least on planet earth. Repeating your sales pitch doesn't make it any more true. I'm not going to bother refuting any of your `arguments'. You didn't listen the last thousand times, so you won't listen now.

Re:Uranium

[Anonymous Coward]

that's 650 years

ONLY 650 years? My god, what will we ever do? If it only lasts 6 centuries then surely it's not a solution for the next 50 years.

You are an idiot with no concept of the vastness of the ocean or the magnitude of energy from the uranium in common dirt.

They are considering the mining of ocean water for lithium, which has a concentration of 1.8e-7 kg/L. Uranium has a concentration of 3.2e-9 kg/L. If it is impractical to extract uranium then it's impractical to extract lithium. Yes, the lithium is not consumed in the making of batteries like uranium is consumed in a reactor. Lithium can be recycled but if we are going to replace every hydrocarbon powered plane, train, and automobile in existence now with a lithium battery equivalent then that's a lot of lithium. Do the math on that, we're talking billions of tons of lithium.

This uranium in the oceans is in ADDITION to existing known sources. I read of people that think fusion is going to save us, but that will quite likely mean the consumption of lithium in the fusion. There's very few fusion reactions that are considered feasible, and lithium is in half of them. Yet it seems no one is concerned with running out of lithium. I haven't done the math on how long known reserves of lithium would last as fusion fuel but I can imagine it would also be in the millions of years, but only a few hundred if we limited ourselves to what we could extract from the ocean.

Re:Uranium

[Anonymous Coward]

Of course, there's technically feasible, and then there is energetically reasonable. Unless there is a positive EROEI (Energy Return On Energy Invested), then there is little point in doing it. Improved technology in various areas might make that likely.

Modern reactor designs can produce 50 to 60 GWh per ton of enriched fuel, so EROEI is hardly a concern.

Re: Uranium

[c6gunner]

Modern reactor designs can produce 50 to 60 GWh per ton of enriched fuel, so EROEI is hardly a concern.

You're an order or magnitude or two off on those numbers. It's 50 gigawatt DAYS per tonne, not hours. So multiply by 24.

But then only about one third of that output is electricity, the rest is heat. So if we care about the electricity it's more like

50*24*0.33
= 396 GWh of electricity per tonne

Plus 804 GWh of thermal energy.

Re: Uranium

[c6gunner]

I'm not going to bother refuting any of your `arguments'. I couldn't make a convincing case the last thousand times, and I can't do it now.

FTFY

Re:Uranium

[tmjva]

I guess that's why the Federation was always mining and trading in di-lithium crystals!  The doubling di- would make them twice as difficult!

"amazing" "next generation" == "press release"??

[davidwr]

When I see buzzwords like this in the first line or two of a summary, I'm wondering if this is real "news for nerds" or a warmed-over press release.

Re:"amazing" "next generation" == "press release"?

[Anonymous Coward]

I don't think you have to wonder about that.

The submittors are not nerds but pluggers or even TFA authors themselves, and the current crop of editors just don't have what it takes.

Enough salt to last forever

[ET3D]

Top Secret said it best.

Re:"amazing" "next generation" == "press release"?

[Anonymous Coward]

This MOF has been around a while and people are still trying to find the killer application for it. An improvement by a factor of 2 or 3 over reverse osmosis as far as power consumption really isn't that significant. How much does the MOF cost? What are the maintenance costs? Longevity?

Efficiency?

[140Mandak262Jamuna]

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.

Re:Efficiency?

[Billly Gates]

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

Re:Efficiency?

[Luckyo]

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.

Re:Efficiency?

[140Mandak262Jamuna]

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.

Re:But can you trust the Chinese?

[Megol]

You mean the Japanese? Or perhaps Americans?

I don't really agree that Americans can't make something significant (though often by importing talent from other countries) and one can't really call them a "race".
And the Japanese have also made significant contributions and still do.

Re: But can you trust the Chinese?

[Anonymous Coward]

Can you trust the Americans? Japanese can't trust the Americans. Chinese can't trust the Americans. Why would you trust the Americans?