Graphene Desalinates Sea Water

Even though the majority of the Earth is covered in water, a surprising number of people around the world don’t have easy access to clean drinking water. The oceans of course are full of salt, and it is difficult to filter that salt out. Researchers at the University of Manchester have found a way to improve a graphene-based filter mechanism that could help convert sea water to potable water.

Pure graphene can do the job, but it is difficult to manufacture in commercial quantities. In addition, the membrane requires the creation of tiny holes, further complicating the production. The new method uses graphene oxide, which is very simple to make and deploy.

Graphene oxide membranes have been used before to filter out small particles, but they swell a bit in the presence of water and that change in properties is enough for salt to get through. The new research shows that constraining the membrane with a wall made from epoxy resin stops the expansion and allows the membrane to block salt.

Traditional graphene oxide membranes can’t block particles smaller than about 9 angstroms. The filter mechanism relies on spacing between layers of the filter which can be as broad as 13.5 angstroms in water. Not only does the new technique allow a spacing as low as 6.4 angstroms, but the spacing can be tuned for different purposes. The new filters can reject up to 97% of the salt in water.

We’ve seen people collecting water from fog. Of course, sometimes salt water is useful. For example, perhaps you need an antenna at the beach.

34 thoughts on “Graphene Desalinates Sea Water

  1. And of course the remainder higher concentration brine can have the water evaporated to get the salt which can then be processed with sequestered CO2 and bound with waste plastics too in order to produce concrete like building materials tougher than conventional concretes of last century :-)

      1. Incorrect monkeys buggy and dangerous scientific misconduct to spread uninformed claims, please learn about:-
        1. Radiative transfer and the Beer-Lambert relationship never refuted that GHGs interference with long wave radiation to space as confirmed by satellite data And thousands of instruments globally where Beer-Lambert an essential measurement tool. ie. GHG properties evident, never refuted.
        2. Higher CO2 shifts some food plants equilibria to produce cyanogens (poisons ie cyanide and derivatives) eg Cassava and more recently starting to occur in Clover which is food for cattle thus affecting meats. We don’t need more carbs for food we need more proteins for the most part.
        3. Higher CO2 results in faster growth of lignin (key structural component of trees) resulting in less density and greater porosity, the result is easier to catch fire in drier climates and more ferocious fires too such that fires propagate more easily by radiative transfer alone (ie. Not by direct contact) such as across fire breaks and roads – noticed more wildfires last 20 or so years all over the world where it’s drier ?
        4. Higher CO2 lifts H2O which is a more powerful GHG, please learn about psychrometry
        5. In general the changes due to various climate regions and lower crop productivity is resulting in greater use of nitrate fertilisers this means more N2O is being released which is an even more powerful GHG again ie amplifying effect.
        6. Isotopic signature confirm fossil fuels primary cause of higher CO2 in atmosphere since start of industrial revolution also closely correlated with consumption. Eg Humans are burning equivalent of about 230,000 litres of petrol per second each and every second on average as assessed approx 4 years ago it’s now more than that. Work out the molar mass on that accumulation of CO2 in atmosphere if you can !

        It should be obvious to all educated intelligent people that our biosphere has adapted to a level of CO2 which has been stable for millennia before the advent of the industrial revolution, the last 200 years or so rate of change upwards is causing several issues with greater heat retention and uncertainty in food production as well as ocean acidification it is important we reduce CO2 back to those times at the best, the least is sequester CO2 where feasible and best into useful products such as concrete’s etc…

        https://en.wikipedia.org/wiki/Radiative_forcing

        If you can refute just one of the key Physics with evidence then get a Nobel prize and go on speaking tours worldwide and make millions of $ so far millions of physics and other uni students globally in last 30 years failed to refute the AGW issue one bit.

        Incidentally Exxon affirmed AGW circa 1982 back then they had more facilities to confirm GHG issue and other details pointing to the long term dilemma we are in. Go argue with them instead of one line useless blurts on this forum, thanks.

          1. LoL @Brian, to avoid embarrassment in future look at the comment replied to, in this case “monkeys buggy” is the handle/name the poster used making the unfounded unscientific claim I responded to, I followed normal forum style dialectic protocol pasting his handle for audit trail. Its odd though you didn’t notice as that sentence is distinct from the remainder of my post. Funnily enough your comment at first implied you pretended not to understand the content, ie. It’s mostly high school stuff though I am sorry for readers who missed high school and subsequent university experience – that’s the uneducated audience where the bulk of anti AGW and climate change denier emotional propaganda is directed to and further cements the importance of key education in Physics – not to miss reading comprehension and dialectic methods too of course, probably why some Americans have trouble understanding the French ;-)

        1. “you pretended not to understand the content, ie. It’s mostly high school stuff though I am sorry for readers who missed high school and subsequent university experience”

          Mike, you may or may not be a knowledgable guy, but the problem is that your delivery just plain sucks.
          Plenty of people have mentioned this to you over years of your postings but the message hasn’t quite sunk in yet.
          Your info may be valuable, but it’s deliveried in such an unintelligible manner that just puts people’s backs up.

          If you’d been a lecturer at any learning establishment I’ve been to, I fear I and my fellow students would have sought your removal.
          Or drug testing & tin foil hat removal.

          Re your post. TLDR:
          https://xkcd.com/1732/

          Makes more of a point really.

        1. Strange and vague thing to write ???? ????
          You seem to be unaware of the various GHG’s retention periods (and lag times re carbon cycle also under the duress of organic decay at higher temperatures eg permafrosts and hydrates release) and in relation to Psychrometry eg H2O as well as the amplifying effect CO2 has on direct and indirectly related other GHGs. Please clarify your statement as at present one could infer you deny AGW effects or deny subsequent changes in climate but refuse to write that openly and only tangentially to cast aspersions implying fault ?

          Anyone who has the slightest confusion or denial of climate change should read Exxon’s publication circa 1982 affirming fossil fuels and the Physics details of radiative transfer, the essential aspects seem to be covered fairly well in this link, with of course references the most important ‘gold’ to follow up the details…
          https://en.wikipedia.org/wiki/Radiative_forcing

      2. I also tend to agree that CO2 is a necessary molecular for our survival, not our enemy. All life needs carbon, most need oxygen to breath. I very seldom consumed raw carbon, it’s not a normal or natural part of anything’s diet. Plants just happen to be the food for most life on the planet, and they get their carbon from CO2. Plant grown in a greenhouse, with CO2 augmented to 1200-2000 ppm, grow incredibly fast and healthy. Regardless of your dietary choice, plants play a key role in producing your food of choice. Plants also tend to like a warmer climate. Logically, a warmer climate, more CO2, means more food, without all the chemicals and processing to improve yields, artificially. Basically, healthy food for all, healthier planet.

        The scary warm, has only been maybe, 1 degree celsius, since the start of the industrial revolution (couple hundred years). That’s presuming that there is any accuracy to the proxy data used to make such an estimate. I’ll stick with the simple, and obvious, we need the CO2. The GHG is propaganda, for which you need to waste a whole lot of time trying to follow.

      1. Did you try checking with Google before making that post – just select my keywords, there are so many Zerg ?
        Some of this already in text books ie past the peer review stage about using CO2 feedstock. I’d suggest also looking up cement manufacture in conjunction with removing chlorine from brine whilst exposing that and related hydroxides to CO2 as a start in respect of the chemistry permutations and there are heaps of other approaches eg plastic/mineral bindings in constant development and commercial products in select circumstances eg variants of Stucco. Google scholar would be your best source for the key chemistry and studies in concrete production methodology. Here are a few links which can tickle the choice of subsequent Google searches…

        https://www.sciencealert.com/scientists-have-made-concrete-using-plastic-waste-and-it-s-just-as-strong-as-regular-concrete
        https://www.hunker.com/13401286/differences-between-portland-plastic-cement
        https://qz.com/1123875/the-material-that-built-the-modern-world-is-also-destroying-it-heres-a-fix/
        https://www.scientificamerican.com/article/cement-from-carbon-dioxide/
        https://www.cement.org/for-concrete-books-learning/concrete-technology/concrete-design-production/concrete-as-a-carbon-sink
        https://www.zmescience.com/science/news-science/adding-irradiated-plastic-makes-stronger-concrete-cuts-co2-emissions/
        https://phys.org/news/2018-09-plastic-concrete-sustainable-india.html
        https://www.designindaba.com/articles/creative-work/plastic-infused-concrete-could-cut-cement-industry’s-carbon-emissions
        https://www.google.com/url?sa=t&source=web&rct=j&url=https://researchonline.jcu.edu.au/43810/1/43810-yin-2015-thesis.pdf&ved=2ahUKEwiKk86ruvngAhWMA3IKHQgiCFIQFjAFegQIBBAB&usg=AOvVaw1X6E2c691AKrd_kGdrvdOz
        https://www.researchgate.net/publication/283190662_Use_of_different_forms_of_waste_plastic_in_concrete_-_a_review
        https://books.google.com.au/books?id=Dap6DwAAQBAJ&pg=PA605&lpg=PA605&dq=“plastic+concrete”+co2&source=bl&ots=nvOr064s4X&sig=ACfU3U0csRdDIaojKL-ITx-WRmmY8xiCTA&hl=en&sa=X&ved=2ahUKEwjCsOS1u_ngAhUUT30KHY6WABY4ChDoATAQegQIBxAB#v=onepage&q=”plastic%20concrete”%20co2&f=false
        https://www.reddit.com/r/science/comments/78nnde/students_reinforce_concrete_with_plastic_that/
        https://books.google.com.au/books?id=0cxPCgAAQBAJ&pg=PA263&lpg=PA263&dq=“plastic+concrete”+co2&source=bl&ots=dyA5EXHUWT&sig=ACfU3U2nu77e-8NF171QIGZQJEH2bSNKCQ&hl=en&sa=X&ved=2ahUKEwjsz87Xu_ngAhWaYH0KHQZPAIE4FBDoATACegQICRAB#v=onepage&q=”plastic%20concrete”%20co2&f=false
        https://www.google.com/url?sa=t&source=web&rct=j&url=https://barchip.com/wp-content/uploads/2017/09/EPC_PDS_BarChipR65_2017_email.pdf&ved=2ahUKEwjvzrecvPngAhVZWysKHUgCC1E4HhAWMAN6BAgHEAE&usg=AOvVaw3-LVZSspNDhGY__J5P0OqZ
        https://www.science.gov/topicpages/c/cement+manufacturing+plants

  2. The next logical research area would be on the long term health effects of leaked graphene oxide nano particles, slowly fed to living animals in water. Probably minimal effects, but …

      1. Bucky balls (c60 I think) would not have similar effects to graphene. I’m not aware of the possibility of graphene turning into c60, but consider that c60 is a bunch of microscopic balls, a fairly uncommon structure with properties unlike a chunk graphene.

    1. Because the end to end thermodynamic analysis shows the method you suggest and others similar such rely on sizable infrastructure and high energy usage woefully inefficient in contrast to other approaches especially in third world countries across disparate comparatively isolated population groupings…

    2. Yeah that works for all matter recycling requirements, it just happens to be the most expensive option, then again if you had a fusion reactor for the huge energy input and really needed a universal matter recycler to feed into your nano assemblers it would be a perfectly OK solution.

  3. That’s all fine and dandy, but they always assume there’s nothing else in the water than sodium chloride (or other salts). It takes exactly three minutes for all the pores of the filter to become blocked by dirt, microscopic pieces of plastic, bacteria, and algae.

    The salt water needs to be filtered with the finest sieves in the world before it is filtered with this.

  4. You must discuss energy/liter relative to other methods, otherwise this article is useless distraction. The problem of filtering out salt has been solved, but the problem of doing it cheaply and energetically efficiently is not. I don’t think this article should have been posted on Hackaday. Have higher standards and respect the wits of your audience.

  5. Gimmick (not surprising for graphene research).

    Graphene oxide (not graphene) has been around for years, its actually oxidized graphite. Stick a lump of graphite in a bucket of hydrogen peroxide (or whatever) and you have a bucket of graphene oxide. The planar particles you get aren’t exactly well-defined (lots of oxygen bearing functional groups at random positions). Nobody was really interested in oxidized graphite. It had some uses, but was fairly boring. Then graphene (not oxidized graphite) came along as the material with interesting electrical properties that was going to save the world, and now oxidized graphite is coming back out of the woodwork on the back of it, although it has practically none of the interesting electrical properties of graphene (but does share the same word, so people easily get confused between it and graphene. I suggest changing the name of the article).

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