Environment

Highly efficient process makes seawater drinkable in 30 minutes

Highly efficient process makes...
A scanning electron microscope image of metal-organic frameworks
A scanning electron microscope image of metal-organic frameworks
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A scanning electron microscope image of metal-organic frameworks
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A scanning electron microscope image of metal-organic frameworks

Access to clean, safe drinking water is a necessity that’s worryingly not being met in many parts of the world. A new study has used a material called a metal-organic framework (MOF) to filter pollutants out of seawater, generating large amounts of fresh water per day while using much less energy than other methods.

MOFs are extremely porous materials with high surface areas – theoretically, if one teaspoon of the stuff was unpacked it could cover a football field. That much surface area makes it great for grabbing hold of molecules and particles.

In this case, the team developed a new type of MOF dubbed PSP-MIL-53, and put it to work trapping salt and impurities in brackish water and seawater. When the material is placed in the water, it selectively pulls ions out of the liquid and holds them on its surface. Within 30 minutes, the MOF was able to reduce the total dissolved solids (TDS) in the water from 2,233 parts per million (ppm) to under 500 ppm. That’s well below the threshold of 600 ppm that the World Health Organization recommends for safe drinking water.

Using this technique, the material was able to produce as much as 139.5 L (36.9 gal) of fresh water per kg of MOF per day. And once the MOF is “full” of particles, it can be quickly and easily cleaned for reuse. To do so, it’s placed in sunlight, which causes it to release the captured salts in as little as four minutes.

While there’s no shortage of desalination systems in use or development, the team says that this new MOF is faster-acting than other techniques, and requires much less energy throughout the cycle.

Thermal desalination processes by evaporation are energy-intensive, and other technologies, such as reverse osmosis, has a number of drawbacks, including high energy consumption and chemical usage in membrane cleaning and dechlorination,” says Huanting Wang, lead author of the study. "Sunlight is the most abundant and renewable source of energy on Earth. Our development of a new adsorbent-based desalination process through the use of sunlight for regeneration provides an energy-efficient and environmentally-sustainable solution for desalination."

The research was published in the journal Nature Sustainability.

Source: Monash University via Eurekalert

10 comments
yawood
Where do I get it??
buzzclick
As far as I know, seawater can have as much as 35,000ppm of salt. Fresh water should have a maximum of 1000ppm. If this system of metal-organic framework filters can deal with real world applications economically and efficiently, then it's good to go.
Karmudjun
Wasn't there an article about six weeks ago heralding the same thing? I'm hoping that these metallic particles are biologically inert, and I am all for the reduced energy and cost requirements! If this is scalable and feasible we should move to implementing this technology sooner rather than later. My city primarily uses river water through a staged filtration system - sand, activated carbon, UV light, and I don't know what else - but they do reduce the particulate count significantly when they test the water (probably when they have just cleaned the system and renewed the filtration media). I know in parts of our country where fracking has gone on for a while, the well water would benefit from something like this. At least I hope it would. I've never had hydrocarbon gases come out of my tap so I can't fathom what it would take before I'd drink that contaminated water....
wle atlanta
what does 'sunlight' do in the desalination process?
is it just providing heat?
where does the salt go?
do you have to have water to get the salt out?
i cannot imagine it just falls off as some kind of dry powder
wle atlanta
what does the stuff cost?

these articles always leave out the interesting questions

wle atlanta
what do you do if there is not enough 'sunlight'?
how much does it take to clean the filters, for say a gallon of fresh water?
how much water does it take, to produce a gallon of drinkable water?

wle atlanta
does the stuff get worn out, used up?

what is the cost per gallon of drinkable water?
toni24
Does that mean we can have drinking water from the brine on Ceres?
Worzel
Cost of the material manufacture is the critical component, thats not mentioned.
Grunchy
"Sunlight is the most abundant and renewable source of energy on Earth," you would surely be "illuminated" by a visit to sunny old England my friends :)