The Briefing Room
General Category => Science, Technology and Knowledge => Topic started by: 240B on August 16, 2020, 12:33:29 am
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ScienceAlert
DAVID NIELD
15 AUGUST 2020
Technology that can convert salty seawater or brackish water into safe, clean drinking water has the potential to transform millions of lives across the globe, which is why so many scientists are busy working on projects to do just that.
Now, a new innovation developed by scientists in Australia could be the most promising one yet, with researchers using metal-organic framework compounds (or MOFs) together with sunlight to purify water in just half an hour, using a process that's more efficient than existing techniques.
It's cheap, it's stable, it's reusable, and it produces water that meets the World Health Organisation (WHO) standards for desalination. Around 139.5 litres (nearly 37 gallons) of clean water can be produced per day from a kilogram (2.2 pounds) of MOF material, based on early testing.
(more)
https://www.sciencealert.com/new-material-makes-seawater-drinkable-in-minutes-and-is-cleaned-by-sunlight
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If viable, a game changer.
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If viable, a game changer.
True.
If this is verified and actually works, it would change the entire world profoundly forever.
We just have to hope that it is not buried by some billionaire or a major power.
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BM
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The article did not give enough details to determine if it can be viable option or not. The first problem off the top of my head will be how many times can the system be regenerated before it fails. Another is what is the efficiency loss after regenerating? Nothing is 100% efficient and everything loses capacity as it is used. Also the dumbass writer talked about installing it in water pipes and pumping seawater directly into a building, which means you will need a dedicated maintenance staff to remove the filter for regeneration on a regular basis. Another is what is the cost to manufacture? Does it use a lot of rare, expensive metals?
I see the same hype I saw with the first non lead-acid batteries back in the late 1970's. A LOT of talk about how the nickel hydride batteries were a game changer, then nothing after it was found they became bricks after a few discharge-charge cycles. In my old cynical engineer's brain, I bet this new wonder substance meets the same fate.
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The article did not give enough details to determine if it can be viable option or not. The first problem off the top of my head will be how many times can the system be regenerated before it fails. Another is what is the efficiency loss after regenerating? Nothing is 100% efficient and everything loses capacity as it is used. Also the dumbass writer talked about installing it in water pipes and pumping seawater directly into a building, which means you will need a dedicated maintenance staff to remove the filter for regeneration on a regular basis. Another is what is the cost to manufacture? Does it use a lot of rare, expensive metals?
I see the same hype I saw with the first non lead-acid batteries back in the late 1970's. A LOT of talk about how the nickel hydride batteries were a game changer, then nothing after it was found they became bricks after a few discharge-charge cycles. In my old cynical engineer's brain, I bet this new wonder substance meets the same fate.
Spent my entire career in the environmental profession, and dealt with water issues, at the industrial and municipal levels. And I'll just say this article teems a little more of snake oil than science. There is more than desalination involved. There is disinfection, and once you get past the biological aspects, does this metal technology have any leachable components that make the water harmful toxic? And finally you have the issue of aesthetics. Just because it is drinkable, doesn't make palatable (unless you are terribly dehydrated).
Color me a tad skeptical at this point
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The article did not give enough details to determine if it can be viable option or not. The first problem off the top of my head will be how many times can the system be regenerated before it fails. Another is what is the efficiency loss after regenerating? Nothing is 100% efficient and everything loses capacity as it is used. Also the dumbass writer talked about installing it in water pipes and pumping seawater directly into a building, which means you will need a dedicated maintenance staff to remove the filter for regeneration on a regular basis. Another is what is the cost to manufacture? Does it use a lot of rare, expensive metals?
I see the same hype I saw with the first non lead-acid batteries back in the late 1970's. A LOT of talk about how the nickel hydride batteries were a game changer, then nothing after it was found they became bricks after a few discharge-charge cycles. In my old cynical engineer's brain, I bet this new wonder substance meets the same fate.
Here's a story with a bit more detail @Joe Wooten https://www.monash.edu/news/articles/breakthrough-technology-purifies-water-using-the-power-of-sunlight (https://www.monash.edu/news/articles/breakthrough-technology-purifies-water-using-the-power-of-sunlight)
Still leaves a lot of questions to be answered if you ask me.
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Here's a story with a bit more detail @Joe Wooten https://www.monash.edu/news/articles/breakthrough-technology-purifies-water-using-the-power-of-sunlight (https://www.monash.edu/news/articles/breakthrough-technology-purifies-water-using-the-power-of-sunlight)
Still leaves a lot of questions to be answered if you ask me.
Thanks for the link. Very vague on the details, but it sounds like a catalytic process. One red flag for me that came up, was the fact they stated that media (catalyst) could regenerate in 4 minutes in sunlight. I find that hard to believe, as most catalyst regenerant needs have a much higher temperature and retention time requirement. Maybe I am missing something here, but I just don't buy it.
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Thanks for the link. Very vague on the details, but it sounds like a catalytic process. One red flag for me that came up, was the fact they stated that media (catalyst) could regenerate in 4 minutes in sunlight. I find that hard to believe, as most catalyst regenerant needs have a much higher temperature and retention time requirement. Maybe I am missing something here, but I just don't buy it.
Toward the bottom of the article there is a link that allows downloading the study. I may do that later.
Belay that! It's pay for play and I'm not playing.
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A sunlight-responsive metal–organic framework system for sustainable water desalination
https://www.nature.com/articles/s41893-020-0590-x (https://www.nature.com/articles/s41893-020-0590-x)
Abstract
Light-responsive materials with high adsorption capacity and sunlight-triggered regenerability are highly desired for their low-cost and environmentally friendly industrial separation processes. Here we report a poly(spiropyran acrylate) (PSP) functionalized metal–organic framework (MOF) as a sunlight-regenerable ion adsorbent for sustainable water desalination. Under dark conditions, the zwitterionic isomer quickly adsorbs multiple cations and anions from water within 30 minutes, with high ion adsorption loadings of up to 2.88 mmol g−1 of NaCl. With sunlight illumination, the neutral isomer rapidly releases these adsorbed salts within 4 minutes. Single-column desalination experiments demonstrated that PSP–MOF works efficiently for water desalination. A freshwater yield of 139.5 l kg−1 d−1 and a low energy consumption of 0.11 Wh l−1 would be reached for desalinating 2,233 ppm synthetic brackish water. Importantly, this adsorbent shows excellent stability and cycling performance. This work opens up a new direction for designing stimuli-responsive materials for energy-efficient and sustainable desalination and water purification.
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A sunlight-responsive metal–organic framework system for sustainable water desalination
https://www.nature.com/articles/s41893-020-0590-x (https://www.nature.com/articles/s41893-020-0590-x)
Cationic and Anionic beds in tandem have been used for decades in industrial water prep, and in desalination plants in the Middle East. Ion exchange resins are extremely expensive, need clean water for backwash, and have several other ancillary processes involved for water treatment. I wish these guys the best, and I hope they are on to something, but am of the coronary.... If it seems to good to be true.....
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A (leading) technology is from Israel. Plants in Florida, Calsbad CA (operating) and Huntington Beach CA. (future).
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Cationic and Anionic beds in tandem have been used for decades in industrial water prep, and in desalination plants in the Middle East. Ion exchange resins are extremely expensive, need clean water for backwash, and have several other ancillary processes involved for water treatment. I wish these guys the best, and I hope they are on to something, but am of the coronary.... If it seems to good to be true.....
You are talking about a water softner which removes mainly calcium ions and replaces them with sodium (salt) ions. What we are talking about here is removing salt not adding it.
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What is not being said:
1) If sunlight causes the substrate to release the salt, you still need to backwash it out. Maybe you can use high pressure air.
2) Sea water does not contain just sodium chloride, but other salts, metals, and organic materials. It will need pre-filtering first which requires pumping it through a sand bed filter at the minimum.
3) How long does the system last before it need replacing?
4) Maintenance - lab research by scientists never take this into account. They leave it to the engineers brought in to try commercializing their research. Maintenance is usually the biggest budget item in a plant.