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

bbc.com

71–80 of 117 posts

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

#71

This is all fine, but if it isn't inert and if it 'leaks' graphene, it can be super toxic as well. I don't want to pu-pu it, but it is legitimate concern.

I didn't know that graphene was toxic. I should stop licking my pencils. And from what little chemistry I know, I though graphene oxide was rather inert.

Graphene != graphite

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

#72
Back at university I dreamt of creating bacteria to do desalination, powered by the sun. All the necessary components exist–in fact, a seemingly endless number of genes code for channels and transports that selectively target the charged ions (Na^2+, Cl- mostly, but also Potassium and Magnesium). It's partially the legacy of life having arisen in saltwater, and many biological processes are controlled with ion concentration gradients. Signal transmission along a nerve? -> Ions. Want to get all this water out of here? -> Transport the salt across the membrane, and the water follows voluntarily.

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

#73

This is somewhat OT, but I've noticed a trend -- although I can't say how recent -- of headlines of the form "British [X] do [Amazing Thing]", particularly (but not necessarily) from the BBC. I note that the HN headline has been changed to "UK researchers" (IIRC, it said "British Scientists" earlier) and this BBC article doesn't actually use this phrase in their headline, but it appears prominently in the tagline. Th…

> in a time when populist nationalism is causing all kinds of problems

(I realize this forum will be almost overwhelmingly in favor of the above statement, but thought I would respond anyway to give an alternative viewpoint from outside).

What problems? Is it really causing problems, or is it just that you are politically opposed to it? The lack of nationalism I would say has caused far more problems over the last few decades (Mass clashing of cultures, rise of terrorism, global multi-nationals exploiting workers, not paying taxes etc, moving democracy and accountability further and further away from people).

If a family member achieved something you would naturally feel more "proud" than if it was a person in the world picked at random.

For some people, their nationality is important to them - an extended family of shared identity, culture, experiences and values. I would much much rather use a local taxi company, which will benefit my local community, friends, family, than use some faceless global thing like Uber, which will benefit some rich people in another country.

Further, competition is good. It's the way we achieve things. If a team of scientists in [other_country] see this news, they will likely be spurred on.

This is why things like the space race worked so well.

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

#74

This is somewhat OT, but I've noticed a trend -- although I can't say how recent -- of headlines of the form "British [X] do [Amazing Thing]", particularly (but not necessarily) from the BBC. I note that the HN headline has been changed to "UK researchers" (IIRC, it said "British Scientists" earlier) and this BBC article doesn't actually use this phrase in their headline, but it appears prominently in the tagline. Th…

> in a time when populist nationalism is causing all kinds of problems (I realize this forum will be almost overwhelmingly in favor of the above statement, but thought I would respond anyway to give an alternative viewpoint from outside). What problems? Is it really causing problems, or is it just that you are politically opposed to it? The lack of nationalism I would say has caused far more problems over the last fe…

Well it's causing the UK to leave the EU which is a disaster by any measure, not including idiots wanting "control".

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

#75

Earlier quoted context omitted.

> in a time when populist nationalism is causing all kinds of problems (I realize this forum will be almost overwhelmingly in favor of the above statement, but thought I would respond anyway to give an alternative viewpoint from outside). What problems? Is it really causing problems, or is it just that you are politically opposed to it? The lack of nationalism I would say has caused far more problems over the last fe…

Well it's causing the UK to leave the EU which is a disaster by any measure, not including idiots wanting "control".

> Well it's causing the UK to leave the EU which is a disaster by any measure, not including idiots wanting "control".

So you're just politically opposed to it.

It's not a disaster if you're very much opposed to an EU superstate.

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

#76

Earlier quoted context omitted.

Well it's causing the UK to leave the EU which is a disaster by any measure, not including idiots wanting "control".

> Well it's causing the UK to leave the EU which is a disaster by any measure, not including idiots wanting "control". So you're just politically opposed to it. It's not a disaster if you're very much opposed to an EU superstate.

This is just a slippery slope fallacy. There was clear opposition to an EU superstate in many countries, there's no way the UK ever would have ended up in one. If anything, this makes a (smaller) EU superstate more likely.

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

#77
post #66
post #61

Earlier quoted context omitted.

Zhang's. They're built to withstand magnitude 9.0. https://www.wired.com/2012/09/broad-sustainable-building-ins... https://www.theguardian.com/world/2015/apr/30/chinese-constr...

They might be designed to withstand magnitude 9.0, whether they actually are built that way is a different question.

Indeed; I would assume a big part of the bureaucratic layer exists to make everything work mostly correct even though there will be cheaters and thieves at every stage of the construction process.

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

#78

This is somewhat OT, but I've noticed a trend -- although I can't say how recent -- of headlines of the form "British [X] do [Amazing Thing]", particularly (but not necessarily) from the BBC. I note that the HN headline has been changed to "UK researchers" (IIRC, it said "British Scientists" earlier) and this BBC article doesn't actually use this phrase in their headline, but it appears prominently in the tagline. Th…

It's an item on BBC radio news today. And as I half listen to the radio the impression it gives is of the Brits making a breakthrough. Maybe Manchester Uni's marketing dept talk to the Beeb and got it on there. Who knows?

As I heard it I thought, this is an odd story. Firstly for the nationalist rhetoric, and secondly for the way it's phrased. It gives the impression of a sieve, much like a kitchen sieve, that can be used to instantly turn sea water into drinking water. Which is nowhere near the truth as far as I can tell.

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

#80

Back at university I dreamt of creating bacteria to do desalination, powered by the sun. All the necessary components exist–in fact, a seemingly endless number of genes code for channels and transports that selectively target the charged ions (Na^2+, Cl- mostly, but also Potassium and Magnesium). It's partially the legacy of life having arisen in saltwater, and many biological processes are controlled with ion concen…

This is interesting to think about. As I'm sure you've considered, bacteria and other living cells exist in a state of highly regulated homeostasis. In bacteria, things like charged ion concentrations are maintained internally by various physiological mechanisms (chiefly the membrane-bound transport channels you describe) at specific concentrations with little variation. Salinity concentrations are generally the same as the surrounding seawater (marine bacteria are usually osmoconformers, as opposed to more sophisticated osmoregulators like fish), and the transport mechanisms exist as adaptations to maintain this state.

So while some aquatic bacteria can exist at a wide range of external salt concentrations (they are "euryhaline"), I don't know of any bacteria that have adaptated to actively concentrate salt internally above the salinity of typical seawater. Beyond a certain not-very-useful threshold, this would disrupt too many metabolic pathways and kill the bacterium. So I don't see how a concentrate-in-the-bacteria-then-filter-them-out approach to industrial desalination would work.

You might be thinking about brine pool extremophile bacteria / archaea, but again, they are just well-adapted when it comes to expelling salt or resisting salt intake, not actively concentrating it internally.

However, if you could embed euryhaline bacteria into some kind of impermeable membrane in a controlled orientation, and engineer them to express the right kind of one-way channels on opposite sides of the cell... there are some big bioengineering obstacles to doing this, but it's an interesting idea. It would basically be a sped-up version of the double reverse osmosis desalination approach already widely used, potentially more efficient and available to be powered more easily by sustainable / free energy sources.

I'm just typing as I think there, so maybe there's been work in this area already.

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