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UK researchers create graphene-based sieve that can remove salt from seawater

bbc.com

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Re: UK researchers create graphene-based sieve that can remove salt from seawater

#41

Post by weaksauce »

Gibbon1 wrote: post #37
weaksauce wrote: post #36

Earlier quoted context omitted.

Why wasn't the flushing automated? edit: I have worked on many RO systems and we always did auto flushing and I am not sure I ever saw anything other than that. It was pharma though.

Likely the issue is, with a large RO plant you hire people for the specific domain knowledge and develop a work culture around it. For a place like an oil rig none of this specific domain knowledge is central to the work at hand. So the technology isn't reliable in that context.

I suppose it's probably something along those lines or the fact that the end product doesn't(to my knowledge) reflect the RO unit working correctly. With pharma they need RO to feed to WFI to use to make the drugs or do their research and it needs to work every day. Still seems like a simple RO system with a basic PLC would work fine on a ship to supply drinking water.

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#42

Post by marmshallow »

jessriedel wrote: post #15
M_Grey wrote: post #5

I swear I've heard about this before... is this one of those stories that emerges about a technology that never seems to enter the market? That "super slick" coating for condiment container interiors is another that springs to mind.

Desalinization is already with about a factor of 2 or 3 of the thermodynamic optimum, so improvements can't be revolutionary. Desalinization mostly needs cheap clean energy.

Can you describe this thermodynamic optimum or link me to something? Curious

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#43

Post by [deleted] »

jessriedel wrote: post #15
M_Grey wrote: post #5

I swear I've heard about this before... is this one of those stories that emerges about a technology that never seems to enter the market? That "super slick" coating for condiment container interiors is another that springs to mind.

Desalinization is already with about a factor of 2 or 3 of the thermodynamic optimum, so improvements can't be revolutionary. Desalinization mostly needs cheap clean energy.

[deleted]

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#44

Post by leot »

jessriedel wrote: post #15
M_Grey wrote: post #5

I swear I've heard about this before... is this one of those stories that emerges about a technology that never seems to enter the market? That "super slick" coating for condiment container interiors is another that springs to mind.

Desalinization is already with about a factor of 2 or 3 of the thermodynamic optimum, so improvements can't be revolutionary. Desalinization mostly needs cheap clean energy.

Even with forward osmosis?

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#45

Post by ghaff »

Gibbon1 wrote: post #37
weaksauce wrote: post #36

Earlier quoted context omitted.

Why wasn't the flushing automated? edit: I have worked on many RO systems and we always did auto flushing and I am not sure I ever saw anything other than that. It was pharma though.

Likely the issue is, with a large RO plant you hire people for the specific domain knowledge and develop a work culture around it. For a place like an oil rig none of this specific domain knowledge is central to the work at hand. So the technology isn't reliable in that context.

Exactly. It was a small scale system and the rig mechanic or whoever was supposed to do it as one of their 100 or so responsibilities so it often wasn't done. It was also pretty much a V1 system so it was just very sensitive.

To set some context that people here might appreciate, there wasn't a single computer or data link to offshore drilling rigs at that time. We were just starting to play with radio modem links.

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#46

Post by dghughes »

M_Grey wrote: post #5

I swear I've heard about this before... is this one of those stories that emerges about a technology that never seems to enter the market? That "super slick" coating for condiment container interiors is another that springs to mind.

I wasn't aware there was a condiment interior sticking problem. Weird.

If this is made the makers better warn first or that ketchup is going to fly out like a rocket.

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#48

Post by sirpros »

mrcactu5 wrote: post #8

we have experienced droughts in Puerto Rico. this could likely lower our water prices as well. http://www.noticel.com/noticia/177413/la-sequia-es-para-larg...

As many drought hot spots around the Globe. I hope this gets the traction it really deserves

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#49

Post by jessriedel »

leot wrote: post #44
jessriedel wrote: post #15

Earlier quoted context omitted.

Desalinization is already with about a factor of 2 or 3 of the thermodynamic optimum, so improvements can't be revolutionary. Desalinization mostly needs cheap clean energy.

Even with forward osmosis?

Not really. Basic thermodynamics tells you that if your only input is water with a certain salt concentration and your output is water with a lower salt concentration (plus either brine -- very salty water -- or dry salt), then there is a minimum free energy cost.

> Based on thermodynamic principles and practical kinetic requirements, the theoretical minimal energy for desalination with FO is always higher than that without FO. In other words, using FO cannot reduce the minimum energy of separation.

https://www.researchgate.net/profile/Shihong_Lin/publication...

The idea behind forward osmosis is to replace the salt in water with some other solute, like sugar. A strict 1-particle-to-1-particle replacement can (I think) have arbitrarily low free energy cost, but then you're just stuck with sugar water instead of salt water. In certain special cases this is fine (like for emergency water generation at sea, when you don't mind drinking sugar water). Insofar as low levels of sugar can't be tasted, and insofar as you have access to free sugar, you can avoid the energetic cost of removing some of the salt by replacing it with sugar. But I don't think this is very much before it becomes noticeable, and sugar isn't free.

If you happen to have excess thermal energy from some source, there are also ways to harvest some of this using forward osmosis, but this is really just another way to smuggle in free energy. In principle, you could use the heat gradient to generate electricity and then use that to power normal reverse osmosis, although which is more efficient will depend on the details of your equipment losses.

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#50

Post by sirpros »

threeseed wrote: post #19
mgberlin wrote: post #10

tl;dr: A material was produced on a very small scale, which, with no regard to the energy required, might be able to remove 97% of the salinity. I.e. science-ey click-bait with a bullshit title.

1. This is the BBC. They aren't a clickbait site. 2. I count about 12 words you can fit into the title. How else can you adequately describe what the article was about ? Their choice seems completely reasonable. 3. The scale and energy required are irrelevant. The article wasn't describing a fully fledged product it was discussing a concept.

I could up vote your response a few more times if it was legal.
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