Graphene-based sieve turns seawater into drinking water

jordanbasset

jordanbasset

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Early days yet and still some technical issues to sort out but this could be very useful in the future
http://www.bbc.com/news/science-environment-39482342
''A UK-based team of researchers has created a graphene-based sieve capable of removing salt from seawater.
The sought-after development could aid the millions of people without ready access to clean drinking water.
The promising graphene oxide sieve could be highly efficient at filtering salts, and will now be tested against existing desalination membranes.
It has previously been difficult to manufacture graphene-based barriers on an industrial scale.''
 
I read that but it didn't really explain the advantage expected over conventional membranes there were hints at speed improvement, less power? and reduced cost of membranes all obviously leading to cheaper desalination. It would have been better if there were indications as to how they could be achieved, unless I missed something. Academically it's very interesting and graphene technology is in it's infancy and I am sure will expand with many more uses.
 
Yes early days, but if it is right that ''water molecules flow exceptionally fast through the membrane barrier'' it may do away with the need for a high pressure and rather expensive pump that is required for current water makers. Suspect it will be a few years away from a practical application though.
 
The interview of the lead scientist on Radio 4 this morning was very unsatisfying. :(

The interviewer asked something like "so the new membrane just acts like a sieve and that you put seawater in the top and clean water runs out the bottom". The scientist replied, "yes, that's right, with some pressure applied to push the water through".

I thought the next question was bound to be "How much pressure are we talking about?"

Fat chance! :rolleyes:

Richard
 
RichardS said:
The interview of the lead scientist on Radio 4 this morning was very unsatisfying. :(

The interviewer asked something like "so the new membrane just acts like a sieve and that you put seawater in the top and clean water runs out the bottom". The scientist replied, "yes, that's right, with some pressure applied to push the water through".

I thought the next question was bound to be "How much pressure are we talking about?"

Fat chance! :rolleyes:

Richard
Click to expand...

James Burke where are you when you are needed.
 
RichardS said:
The interview of the lead scientist on Radio 4 this morning was very unsatisfying. :(

The interviewer asked something like "so the new membrane just acts like a sieve and that you put seawater in the top and clean water runs out the bottom". The scientist replied, "yes, that's right, with some pressure applied to push the water through".

I thought the next question was bound to be "How much pressure are we talking about?"

Fat chance! :rolleyes:

Richard
Click to expand...
I think you are assuming the research is more advanced than it really is. This seems like a very important step but a long way to go before production.

The implication is that any pressure will be low
 
Why would the pressure be low unless the membrane is very thin i.e. 1 or 2 molecules thick in which case it would be remarkably fragile.
 
petehb said:
Why would the pressure be low unless the membrane is very thin i.e. 1 or 2 molecules thick in which case it would be remarkably fragile.
Click to expand...
The whole point about graphene is that it is only 1 molecule thick but it can be supported on a porous substrate to provide mechanical strength
 
RichardS said:
Surely it is the failure to ask searching questions which leads to assumptions being made, not the reverse?

Richard
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A bit unfair on the interviewer. Without our sailing connection would most people here know about the pressures required with existing water making technology?

It does state "minimal energy input" that would be incompatible with using high pressure
 
I'd wager that there's nothing new about this idea.

The first words that sprang to mind when it was mentioned on the news was "semi-permeable membrane". I have no doubt at all that this is just an implementation of a semi-permeable membrane to purify water, using graphene as the membrane. It must have taken all of five minutes for the scientists to come up with the idea after they invented graphene :rolleyes: The fact that it's making the news is probably just an indication that someone's looking for project funding.
 
elton said:
I'd wager that there's nothing new about this idea.

The first words that sprang to mind when it was mentioned on the news was "semi-permeable membrane". I have no doubt at all that this is just an implementation of a semi-permeable membrane to purify water, using graphene as the membrane. It must have taken all of five minutes for the scientists to come up with the idea after they invented graphene :rolleyes: The fact that it's making the news is probably just an indication that someone's looking for project funding.
Click to expand...
You could try reading the article before commenting.
 
RichardS said:
Surely it is the failure to ask searching questions which leads to assumptions being made, not the reverse?
Click to expand...

Yes, the question should certainly have been asked, even if the answer was a "don't know". It's not clear whether the reporter interviewing Dr Nair was the science editor credited with the article, or simply someone from BBC News. It's a bad do if the former.

The author of the piece is on Twitter, so presumably can be asked: http://twitter.com/rincon_p

The main thrust of the piece was the provision of clean water in the Third World, in which case energy needs are critical. It may be that a simple column of water could provide sufficient pressure. Or not. Either way it's of pressing interest.
 
bedouin said:
You could try reading the article before commenting.
Click to expand...

I didn't need to read it. There is nothing new about the idea. The press are focusing on the fact that the membrane can purify water; surely we all knew that? The "innovation" is that they can implement a semi-permeable membrane with graphene. There are dozens of materials that can act as SPMs, as nature discovered billions of years ago. The scientist still can't say if they can construct a SPM using graphene, cheaper than using something else. It's a complete non-story.
 
Really? Name one semi permeable membrane in nature that can do reverse osmosis. I only know ones that can do osmosis.

I thought you could only get osmosis to reverse if there was a huge pressure differential over the membrane greater than the salinity gradient. My reading of this graphene development was that it could 'filter out salts' without the application of high pressure. That is, it's getting the same results as reverse osmosis without the energy requirements.
 
Motor_Sailor said:
Really? Name one semi permeable membrane in nature that can do reverse osmosis. I only know ones that can do osmosis.

I thought you could only get osmosis to reverse if there was a huge pressure differential over the membrane greater than the salinity gradient. My reading of this graphene development was that it could 'filter out salts' without the application of high pressure. That is, it's getting the same results as reverse osmosis without the energy requirements.
Click to expand...

Sorry, but you don't know what your on about.
 
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