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

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.

[0] http://imgur.com/a/LNWUz

[edit]

To summarise, they prepared graphene oxide laminates using vacuum filtration, and then stored them at different relative humidities by changing the salt concentration of the storage liquid. The different relative humidities cause different layer spacing, which they measure with X-ray diffraction, and choose whichever layer spacing they want before adding the epoxy.

The relevant quote from the paper:

Thick (≈100 µm) GO laminates were prepared by vacuum filtration of aqueous GO solutions, as reported previously. The laminates were cut into rectangular strips (4 mm × 10 mm) and stored for one to two weeks at different relative humidities (RH), achieved using saturated salt solutions. The resulting interlayer spacing was measured by X-ray diffraction as shown in Fig. 1e and varied from ≈ 6.4 to 9.8 Å with RH changing from zero to 100%. GO laminates soaked in liquid water showed d ≈ 13.7 ± 0.3 Å. All these values agree with previous reports, where the changes in d were attributed to successive incorporation of water molecules into various sites between GO sheets. Individual GO strips with desirable d were then encapsulated and stacked together using Stycast epoxy as shown in Figs. 1b,c to increase the available cross-section for filtration to 1 mm (see Methods and supplementary Fig. S1). The stacked GO laminates, now embedded in the epoxy (Fig. 1c), are referred to as physically confined GO (PCGO) membranes because the epoxy mechanically restricts the laminate’s swelling upon exposure to RH or liquid water (Methods). The stacks were glued into a slot made in either metal or plastic plate (Fig. 1b). Two sides of these stacked PCGO membranes were then trimmed off to make sure that all the nanochannels are open (Fig. 1d) before carrying out permeation experiments, in which ions and water molecules permeates along the lamination direction as shown in Fig. 1a.

In terms of what's new about this - yeah, less pressure and less energy. On boats the prospect of lugging around your own fresh water makes even relatively heavy and power-hungry desalination plants worthwhile, but land-based installations are very much limited by capital costs and energy usage.

A few things I've found:

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

"10 µm few-layered graphene flakes were able to pierce cell membranes in solution"

http://www.kurzweilai.net/graphenes-negative-environmental-i...

"In groundwater, which typically has a higher degree of hardness and a lower concentration of natural organic matter, the graphene oxide nanoparticles tended to become less stable and eventually settle out or be removed in subsurface environments. In surface waters, where there is more organic material and less hardness, the nanoparticles remained stable and moved farther, especially in the subsurface layers of the water bodies."

(also http://online.liebertpub.com/doi/abs/10.1089/ees.2013.0392)

Funny enough, its not actually banned in the USA, just a liability nightmare. I ocasionally still see brake pads with the stuff. I suspect graphine, and other 'nano' materials will be similar in practice.

The surface is fragile, because it's composed of tiny spikes. Rubbing will destroy it. It's hard to fix this, because the property that makes it useful is the same as the one that makes it fragile.

http://www.azonano.com/article.aspx?ArticleID=3677

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

And from what little chemistry I know, I though graphene oxide was rather inert.

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.

> populist nationalism is causing all kinds of problems

That is not a factual statement, it is a subjective political opinion. People on the other side of the fence think the opposite. From whence do you derive this claim to objective truth? Most of your point seems to be built on that statement, but its subjective nature makes it fall apart.

(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.

Fair enough to pick at which adjectives are used. I certainly find the nationality of the researchers more interesting than many other aspects, such as their hair color. Different nations have different cultures and policies towards things. Using nationality as an adjective might lead to productive conversations around how to make the species better. If so, that's a win. If all it does is promote mindless nationalism, it's a loss. So far, I'm not seeing anything to worry about -- and this title is much better than "Several Short, Brown-Haired People just did some Amazing Things with Beakers!" :)

ADD: It seems like my joking title should end with "And you won't believe #7!"

Thanks for your comment. This kinda thing can certainly get out of hand. So far we are very far away from that happening.