New Desalination System Turns Seawater Into Drinking Water and Useful Salts - Including Lithium (rochester.edu) 27
"Scientists have developed a solar desalination system that turns seawater into drinking water without creating environmentally damaging brine," reports ScienceDaily.
"Special laser-textured metal panels use sunlight to evaporate water while automatically moving salt deposits away from the working surface, preventing clogging. The process was successfully tested with water from three oceans and can recover nearly all salts as solids. Those leftover materials could even become a source of valuable lithium for batteries." (The research team was led by University of Rochest professor Chunlei Guo and published their results in the journal Light: Science & Applications.)
The University of Rochester has made an announcement: The technology uses solar panels made of black metal etched with femtosecond lasers to make the surface super light-absorbing and superwicking — or extremely attractive to water. The panels have a laser-treated active region that pulls a thin layer of water across the surface, absorbs nearly all solar radiation, distills the water, and deposits the leftover salts and minerals into the panel's untreated sides or "passive" region so that the salt does not clog the active region and disrupt continuous desalination... Guo's team precisely etched the black metal's grooves so the various salts and minerals in ocean water would simply slough off... [I]t extracts nearly 100 percent of the salts in solid form.
This could not only produce an abundant supply of table salt, but it could also be used to extract more precious minerals, including lithium, which is used in the lithium-ion batteries that power electric vehicles and other electronics. In a related paper in the Journal of Materials Chemistry A, Guo and his colleagues show how they can use the same superwicking solar panels to separate lithium from the rest of other salts in desalination. Embedding nanoparticles made of hydrogen titanate in the tiny grooves of the black metal surface isolates the lithium from other salts and minerals...Using water samples from Great Salt Lake, the researchers extracted about 50 percent of the lithium from the salts left behind by the desalination process. Guo says now that the superwicking desalination technology has been demonstrated in proofs of concept on small-scale devices, he sees the technology inherently scalable, capable of improving global access to drinking water and building more sustainable supply chains for precious minerals.
"The National Science Foundation, the Bill & Melinda Gates Foundation, and Worldwide Universities Network supported this research."
"Special laser-textured metal panels use sunlight to evaporate water while automatically moving salt deposits away from the working surface, preventing clogging. The process was successfully tested with water from three oceans and can recover nearly all salts as solids. Those leftover materials could even become a source of valuable lithium for batteries." (The research team was led by University of Rochest professor Chunlei Guo and published their results in the journal Light: Science & Applications.)
The University of Rochester has made an announcement: The technology uses solar panels made of black metal etched with femtosecond lasers to make the surface super light-absorbing and superwicking — or extremely attractive to water. The panels have a laser-treated active region that pulls a thin layer of water across the surface, absorbs nearly all solar radiation, distills the water, and deposits the leftover salts and minerals into the panel's untreated sides or "passive" region so that the salt does not clog the active region and disrupt continuous desalination... Guo's team precisely etched the black metal's grooves so the various salts and minerals in ocean water would simply slough off... [I]t extracts nearly 100 percent of the salts in solid form.
This could not only produce an abundant supply of table salt, but it could also be used to extract more precious minerals, including lithium, which is used in the lithium-ion batteries that power electric vehicles and other electronics. In a related paper in the Journal of Materials Chemistry A, Guo and his colleagues show how they can use the same superwicking solar panels to separate lithium from the rest of other salts in desalination. Embedding nanoparticles made of hydrogen titanate in the tiny grooves of the black metal surface isolates the lithium from other salts and minerals...Using water samples from Great Salt Lake, the researchers extracted about 50 percent of the lithium from the salts left behind by the desalination process. Guo says now that the superwicking desalination technology has been demonstrated in proofs of concept on small-scale devices, he sees the technology inherently scalable, capable of improving global access to drinking water and building more sustainable supply chains for precious minerals.
"The National Science Foundation, the Bill & Melinda Gates Foundation, and Worldwide Universities Network supported this research."
Hype (Score:5, Informative)
This sounds like someone made minute, non-revolutionary advances on standard de-salination and described it as if they were the first person to invent evaporative desalination. People have been doing sun powered desalination for thousands of years.
Desalination, even by sunlight, is a power intensive process. The reason why it typically creates brine is not because we are too stupid to complete the process. The original method of pure, unaided solar took about 4 hours to take cups of sea water to make one cup of fresh water ( leaving about 1 cup of brine). If you use a standard fire based distillation you can make a gallon and a half by boiling 3 gallons of sea water and collecting the steam. in ONE hour, with no brine.
Instead, we create brine because:
1) It takes more power to evaporate the last bit of water from a brine solution than it takes to remove the first bit of water from regular salt water.
2) Moving the salt is much easier when it has a bit of water in it. It sticks to the container. (This appears to be the only thing they may have advanced on.)
3) The brine is not just table salt, but a mix of everything that was in the water. Mostly Sodium Chloride, but also any living things in the water, and some bromine, magnesium, calcium, sulfates, strontium, fluoride and yes, some lithium. This will be all mixed up, not nicely separated out. A lot of work to get anything useful from it.
Re: (Score:3)
Moving the salt ...
If they replace the salt-water (and wash-away the salt deposits) frequently, the salt water never degrades into a brine solution, making the evaporation more efficient.
It will be cheaper (and slower) than osmosis because it doesn't require a high-pressure pump. On the down-side, large panels will be vulnerable to weather events (wind, rain, hail, freezing temperature).
Re: (Score:2)
If you wash away the salt deposits, that implies using water and thus generating brine. Brushing the salt away might be better. Main thing would be avoiding losing the salt to precipitation, as the idea seems to be to avoid it returning to the ocean.
Figuring out how to economically purify the salts, including separating out the lithium, would be a neat trick.
Re: Hype (Score:3)
Thats how conventional lithium extraction works in the USA. Drilling for salt brine and evaporating it until the brine reaches a specific concentration. Then processing it with heat among other steps.
The alternative is crushing rock in Australia for example.
Re: (Score:2)
Lithium extraction in like half the world, actually.
But despite both being salt water, the mineral waters from the wells have a lot more lithium than salt water.
Re:Hype (Score:4, Insightful)
This sounds like someone made minute, non-revolutionary advances on standard de-salination and described it as if they were the first person to invent evaporative desalination. People have been doing sun powered desalination for thousands of years.
Solving a minute problem is still revolutionary if that minute problem is preventing a process from being viable, which both the brine and the solar efficiency problems very much were.
problem 3 (Score:2)
your problem 3 seems to be a sufficiently solved issue when you buy sea salt.
Re: (Score:2)
That brine could be useful for salinity gradient power – reverse electrodialysis, though if you need to mix in regular water, kinda defeats the process I expect.
Science is evolution , maybe hype is a bit strong.
The focus of this tech feels like getting the salts passively , clean water is a nice by product. They solved the brine problem. Good!
How much do these panels cost to make?
Re: (Score:2)
That brine could be useful for salinity gradient power – reverse electrodialysis, though if you need to mix in regular water, kinda defeats the process I expect.
I think that if you want to generate electricity from sunlight, this is probably strictly worse than PV cells.
How much do these panels cost to make?
They're effectively extremely thin aluminum foil that has been tooled using a femtosecond laser and mounted to some kind of substrate, so the materials are dead cheap. Femtosecond lasers are somewhat uncommon compared to other industrial lasers but not particularly exotic these days; much (most?) LASIK surgery uses them now.
Throughput is a challenge, though -- the lasers remove very small amounts of
Re: (Score:2)
80m 150m
Sigh. that's 80um 150um except imagine it's a micro symbol instead of a normal u
Thanks, slashdot's html sanitizer.
Re: Hype (Score:2)
Slashdots Unicode bugs could be fixed in one minute but nobody bothers.
I canâ(TM)t even write Slashdotâ(TM)s with an apostrophe.
Re: (Score:1)
> The brine is not just table salt, but a mix of everything that was in the water
And IMHO, is we're talking about any sort of volume, then we should be putting all of that back in the sea rather than trying to take anything further from it. Most of the fresh water we've extracted will find its way back to the sea, so then the oceans remain as they are.
I'll bet a couple of things:
1) We don't yet know what the trace materials in sea water are used for by the oceans and the things that live in them - or at
Re:Hype (Score:5, Interesting)
Desalination, even by sunlight, is a power intensive process.
This is 100% the name of the game and why this panel is so neat. It couples several passive techniques together to reduce the amount of power that's needed throughout the various stages of the desalination process. This is just chaining together several efficiency gains into a better method.
1) the panel is super-wicking so it passively pulls a thin layer of seawater over its surface
2) salt crystals passively move towards the outside of the panel along the grooves so no clogging and easier collection
3) the panels can be tweaked to isolate specific minerals like Lithium from other minerals
They are letting science move the seawater and sort the minerals so we don't have to spend the energy and time doing so. less clogs, less power input, useful minerals in the end instead of brine.
Re:Hype (Score:4, Informative)
3) The brine is not just table salt, but a mix of everything that was in the water. Mostly Sodium Chloride, but also any living things in the water, and some bromine, magnesium, calcium, sulfates, strontium, fluoride and yes, some lithium. This will be all mixed up, not nicely separated out. A lot of work to get anything useful from it.
sigh Right there in the summary: "Embedding nanoparticles made of hydrogen titanate in the tiny grooves of the black metal surface isolates the lithium from other salts and minerals"
Re: (Score:2)
This sounds like someone made minute, non-revolutionary advances on standard de-salination and described it as if they were the first person to invent evaporative desalination.
Did they ever use the word "revolutionary" to describe their work? No, of course not. Did they claim to have invented evaporative desalination? No, of course not. It's literally in the very first sentence of their abstract: "Solar-thermal interfacial desalination is a sustainable solution to meet the ever-increasing global freshwater demand." I really wish you wouldn't make things up like that.
So what do they consider to be novel about their work? That's in the second sentence of the abstract: "Howeve
Re:Hype (Score:4, Interesting)
Looks to me like they do not care so much about the water.
The ocean is a massive, liquid periodic table. While the breakthrough at Rochester focuses heavily on lithium for electric vehicles, the underlying physics of the system applies to everything dissolved in seawater.
If we look beyond lithium, the ocean contains a staggering treasury of elements, though they exist in vastly different amounts.
1. The Bulk Resources (Easy to Harvest)
These minerals are highly concentrated and make up the bulk of the solid crust left on the solar panels:
Magnesium (1,300 parts per million): Crucial for lightweight aerospace and automotive alloys. The ocean is already a primary global source for it.
Potassium (380 parts per million): Highly sought after globally as a core ingredient for agricultural fertilizers (potash).
Bromine (65 parts per million): Heavily utilized in industrial flame retardants and electronics manufacturing.
2. The Strategic High-Value Elements (The Real Targets)
These elements are scarcer but incredibly valuable. By adding target-specific nanoparticles to the solar panel's micro-grooves, scientists can create a "molecular sieve" to trap them passively:
Uranium (3 parts per billion): The oceans hold 4.5 billion tons of uranium—enough to fuel nuclear reactors for centuries. Scientists can snag it using amidoxime nanoparticles, which act like molecular velcro for uranium.
Cesium (0.3 parts per billion): Vital for atomic clocks and high-tech electronics. It can be isolated using rigid hexacyanoferrate nano-cages that trap cesium while letting common salt pass through.
Gold (8 parts per trillion): Millions of tons of gold are dissolved in the sea, but it is incredibly sparse. To mine it without processing mountains of standard salt, panels would need thiol (sulfur-based) nanoparticles. Because gold naturally binds to sulfur, the gold atoms would stick directly to the channels while the rest of the salt washes away.
The Big Picture: Instead of a standard desalination plant that just makes water and waste, this technology turns a floating solar array into a multi-tiered refinery. By lining the panel's channels with different nanoparticles sequentially, a single passive device can use sunlight to distill fresh water while sorting lithium, uranium, cesium, and gold into their own separate pockets.
Re: (Score:2)
At small scales.
At large scales, desalination plants use reverse osmosis, which pretty much inherently creates a brine that is released back into the environment. You're not "moving the salt" to any useful industrial process, since it's still rather dilute.
At bes [blackridgeresearch.com]
Re: (Score:2)
Well, it says in the abstract (and they have further detailed calculations in the paper) that they achieved an average desalination rate of 1.76 kg/m^2/h. So that’s about 1 gallon of water in one hour with 2 m^2 panel. That said, they did their tests using a 9 cm^2 panel, so yields may change significantly on scale up. Not sure if that translates into meaningful cost savings at scale, but it does seem like a significant advance in solar desalination technology. It seems like the paper was focused most
Re: (Score:2)
Black metal grooves (Score:5, Funny)
*head bangs in approval*
The most important question (Score:2)
How easily/fast can it scale and be commercialized?
Known to the State of California to cause cancer (Score:3)
And California, in it's infinite stupidity, will refuse to build such plants because it's easier to suck the Colorado River dry and who gives a shit about those other states who depend on it.
Some numbers (Score:2)
The greater metropolitan area of Mexico City uses around 7.5 billion kg (liters) of water per day.
(25,000,000 people using 300 liters)
Lithium is about 100 parts per billion in sea water.
So if you desalinated enough water to supply Mexico city, and sorted off all of lithium, that would be 750 kg per day, or 270 tonnes per year.
Annual global lithium production is about 290,000 tonnes per year.
Desalinate water for all of Mexico city, add an extra 0.1% to lithium production.
Color me unimpressed.