Graphene Membranes Superpermeable to Water

There has also been studies showing you can make a selective filter by making nanotubes with the right diameter to let water through but not larger molecules. In addition because the walls are so "smooth" there is much less pressure to flow the water through then expected.

Although I doubt this orientation will allow for filtering out "helium" as the original posting.

The mechanims that the original posting paper is speculating, it that the way they made the graphene oxide (not pure graphene) membrane, it is has embedded capilaries which when wet (filled with water) allow for nearly unimpeded transport of water, but when these capilaries dry out, their diameter constricts so that nothing gets through (even helium).

So to contrast, the "tubes" are not rigid and the walls are not so "smooth" in this case, the "tubes" are sort of like chinese finger puzzles. When filled with water, allow water to pass easily, but when you try to pull the last bit of water out of them, the diameter constricts and nothing can get past.. Well maybe the chinese finger puzzle analogy was a bad one, but I couldn't think of anything else...

Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/E21m-Z9ngQ4/graphene-membranes-superpermeable-to-water

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