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

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

[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

[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.

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

[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.