Graphene-based sieve turns seawater into drinking water 

Posted: April 3, 2017 by oldbrew in innovation, research

Credit: nationalgeographic.com


The hurdle of scaling up to industrial size awaits, but the idea sounds interesting. They say “The ultimate goal is to create a filtration device that will produce potable water from seawater or wastewater with minimal energy input.”

A UK-based team of researchers has created a graphene-based sieve capable of removing salt from seawater, says BBC News. 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. Reporting their results in the journal Nature Nanotechnology, scientists from the University of Manchester, led by Dr Rahul Nair, shows how they solved some of the challenges by using a chemical derivative called graphene oxide.

Isolated and characterised by a University of Manchester-led team in 2004, graphene comprises a single layer of carbon atoms arranged in a hexagonal lattice. Its unusual properties, such as extraordinary tensile strength and electrical conductivity, have earmarked it as one of the most promising materials for future applications.

But it has been difficult to produce large quantities of single-layer graphene using existing methods, such as chemical vapour deposition (CVD). Current production routes are also quite costly.

On the other hand, said Dr Nair, “graphene oxide can be produced by simple oxidation in the lab”. He told BBC News: “As an ink or solution, we can compose it on a substrate or porous material. Then we can use it as a membrane.”In terms of scalability and the cost of the material, graphene oxide has a potential advantage over single-layered graphene.”

Continued here.

Comments
  1. waterside4 says:

    Thanks Roger, it is nice to read about scientists doing something for the good of mankind.
    Just one quibble. Could you please put a warning sign up to tell us the link was to the biased bbc.
    I went there, and sure enough it led into global warming crap.

    Otherwise good news.

  2. Graeme No.3 says:

    But waterside4, graphene oxide is carbon + oxygen, so the tiny minds at the BBC would have got their knickers in a twist trying to say something good about it.

  3. tom0mason says:

    What is really needed is a sieve that filters out hubristic belief structures from logical scientific reasoning.

  4. Nothing new in this except the nature of the membrane. Osmosis is the natural tendency based on differences of concentration for a fluid (including a gas) to move from a higher concentration to a lower concentration (eg pure water through a membrane to salt water,or helium in a balloon to air). Reverse osmosis is the opposite and requires energy to overcome firstly the osmotic pressure and then the losses through the membrane. I note that the osmotic pressure of ocean water is in the range 2.6 to 3.5 MPa but operational pressures with standard membranes is around 6 MPa.. Membranes need to be robust and need to be cleaned such as by backwashing. They have a limited life.
    At home I have a double filter on the drinking water which uses the water pressure (in my case about 450 kPa). The first filter removes dirt and large molecules. The second filter is amorphous carbon based and can remove chlorine and all pathogens (one can taste the difference). I need to replace the carbon filter after about 12 months.
    I have doubts that a graphene filter which is sufficiently robust will be economical within 10 years.

  5. michael hart says:

    Looks like no change, then. This has been one of the major problems with graphene for many years.

    Similar problems exist for other materials with interesting electrical- and photo-electrical properties: making it is often the easy part, but manipulating it and constructing electrical contacts to act as effective device interfaces is a different kettle of fish. I spent many wasted hours reading papers that described new materials that might have the properties I once desired for enhancing signal-noise in surface plasmon resonance-based analytical devices. The inventors of these mix-and-bake style preparations frequently described the properties of their new materials as “tunable” to the desired outcome, but not one them ever went ahead and actually wrote a paper that demonstated tuning of the properties to achieve an a priori desired outcome.

    All the BBC understands about the matter is that they heard in 2010 some guys in Manchester got a Nobel prize for work on graphene, but normally “carbon” just causes global-warming.
    (Derivatives of graphene were actually synthesized from graphite about two centuries ago, but they couldn’t analyse and identify them adequately with the tools available at the time).

  6. Stephen Richards says:

    I was using molecular sieves in the 70’s. Big problem was the need to outgas them, like diesel particule filtres, every time you use them.

  7. […] Source: Graphene-based sieve turns seawater into drinking water  | Tallbloke’s Talkshop […]

  8. oldbrew says:

    Re. cementafriend says…

    If it ever does work on a big scale, maybe the ‘minimal energy input’ will be better than osmosis?

  9. AlecM says:

    In 1989 I an a colleague patented a ceramic membrane supported Langmuir-Blodgett membrane a few molecules thick, but it was too expensive to bring to market. So this graphene idea is not exactly new and I expect it would be much more expensive.

  10. Brett Keane says:

    What sort of oxide could graphene form, apart from CO/CO2?

  11. TomO says:

    I read the article wondering where the pilot plant might be an which VC outfit had snapped up the academic spin-off concerned.

    It would seem that there isn’t a plant and there’s no private money. That’s not decrying the work but the BBC treatment from Paul Rincon gets way ahead of itself.

    The BBC has covered Israel’s desalination achievements – it would seem logical that the operators of the world’s biggest single desalination plant at Sorek might have an informed independent opinion on this novel graphene oxide sieve and might be worth soliciting some comment….

    Instead we are treated to UN projection and climate change – same old same old

  12. suricat says:

    Hi oldbrew!

    Just got back from the North of England at 01:00 today (my ‘sabbatical’ to honour Mum’s memory with floral attributes at her memorial site in Tow Law [I visited ‘bruv’ Alan’s site of ash dispersal at ‘Allensford’ on the river Derwent as well while I was near to it]), I’m content. 🙂

    ‘Graphine’ is a newly ‘highlighted’ ‘element’! ‘Graphine oxide’ is a ‘compound’ and ‘not an element’! Sigh. Why do the BBC generate confusion? Probably because they ‘report news’ and don’t know any better. 😦

    Do you want this thread to distinguish the basic differences between ‘filtration’ and ‘de-ionisation’ oldbrew? ‘Filters’ can’t remove/isolate ‘ionic salts’, and ‘de-ionising plant’ can’t remove ‘inert particulates’.

    However, ‘all’ separation systems require a ‘flush cycle’ to permit the active medium’s ‘unrestricted’ efficacy.

    Best regards, Ray.

  13. oldbrew says:

    A graphene-based electrode gets tried out for the solar scene…

    Fern-inspired electrode could boost solar power by 3000 percent

    RMIT’s Professor Min Gu said the new design drew on nature’s own genius solution to the challenge of filling a space in the most efficient way possible — through intricate self-repeating patterns known as “fractals”.

    http://www.sott.net/article/347266-Fern-inspired-electrode-could-boost-solar-power-by-3000-percent

  14. Oldbrew. I think you misunderstand, A molecular sieve is just a special membrane. There is still the need to over come the “chemical” forces of reaction, dilution etc.to go to a lower level of entropy For example under specific conditions of temperature and concentrations, carbon in what ever state will react with oxygen to give CO2. As the reaction is exothermic once started the reaction will continue within concentration ranges It requires much more energy to reverse the reaction. If the starting form of carbon was diamond, the amount of energy required to recover diamonds from CO2 is huge.
    I said that there is a natural tendency of water to dilute brine or seawater. To recover water from seawater it is necessary, for a start, to over come the osmosis pressure. The osmosis pressure is lower for less saline liquids such as ground waters which have salt levels just above drinking levels.while on the other hand it is more difficult to extract pure water from the “dead” sea than from normal seawater.
    In comparison to engineers there are very few scientists who understand processes where there are physical changes and the application of forces and energy.. Combustion and the recovery of energy is engineering.

  15. oldbrew says:

    Here’s the supplementary info file from the researchers:

    Tunable sieving of ions using graphene oxide membranes
    http://www.nature.com/nnano/journal/vaop/ncurrent/extref/nnano.2017.21-s1.pdf

  16. suricat says:

    oldbrew says: April 5, 2017 at 7:16 pm

    “A graphene-based electrode gets tried out for the solar scene…
    Fern-inspired electrode could boost solar power by 3000 percent”

    This is ‘woo woo’ to this thread oldbrew. Why don’t you open a ‘new thread’ on this subject? Please come back TB!

    ‘Graphine’, per se, isn’t “Graphine oxide”! ‘Graphine’ is an ‘element’ and “Graphine oxide” is a ‘compound’ of the product. Thus, ‘Graphine oxide’ exhibits ‘other properties’ than “Graphine” per se!

    You’re ‘pushing the limits’ of plausible chemistry beyond the limits of known interactions with your supposition OB. How can you rationalise/explain your POV?

    Best regards, Ray.

  17. oldbrew says:

    Post says: ‘they solved some of the challenges by using a chemical derivative called graphene oxide.’

    Clear enough?

  18. suricat says:

    oldbrew says: April 7, 2017 at 9:09 am

    “Post says: ‘they solved some of the challenges by using a chemical derivative called grapheneoxide.’
    Clear enough?”

    No! If its ‘graphene oxide’ (graphine oxide) it isn’t ‘graphine’!

    ‘Graphine’ is ~inert, but derivatives of graphine may well exhibit ‘ionic properties’.

    This makes ‘graphine’ a suitable candidate for ‘filtration’, but ‘ionic properties’ added to the ‘filtration property’ of graphine advances the use of graphine into the realm of ‘de-ionisation plant’.

    A ‘DI’ (De-Ionisation) plant requires the implementation of both a ‘cation’ and an ‘anion’ ‘bed/process’.

    I’ll not go into this process further unless you request it OB.

    Best regards, Ray.

  19. oldbrew says:

    No! If its ‘graphene oxide’ (graphine oxide) it isn’t ‘graphine’!
    – – –
    We all know that, what’s the problem? The article refers to a ‘promising graphene oxide sieve’.

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