Access to potable water is especially critical near the ocean, where overuse of wells can depress the freshwater table and allow saltwater to creep in. Desalination isn’t accessible to everyone though, due to the size and expense of desalination plants.
Water filters can be used to remove contaminants from water, including most protozoa, bacteria, and some larger viruses. Removing salt from seawater requires a filter on an entirely different scale. Reverse osmosis desalination systems use a membrane [filter] that separates seawater on the ionic level.
Graphene has been proposed as a potential replacement filter, which could reduce the size of desalination plants, and therefore the overall costs associated with them. Researchers collaborating between the University of Texas at Austin and University of Marberg in Germany, have been focusing on an electrochemical solution.
The “water chip” develops an electrical field that deionized the water, forcing salt ions out of seawater and allowing freshwater to exit via one channel. It runs off just 3V, which puts it well within the realm of possibility that almost anyone could afford a tiny solar panel or a couple of “D” batteries, but there’s a catch to this tiny desalination chip.
The startup company formed to develop the technology, Okeanos Technologies, says the chip only runs at 25% efficiency, so it could be more efficient. Also, more importantly, it only works on one nanoliter [one billionth of a liter] at a time. One press release explained it this way,”Like a troll at the foot of the bridge, the ion depletion zone prevents salt from passing through, resulting in the production of freshwater.”
If this product is going to be useful, that’s going to take a lot of nanotrolls, or at least more-efficient ones, but Okeanos is confident they can scale up the device and make it more efficient. The power requirements are encouraging, but since this works on the nanoscale, won’t it also require water filtration systems to keep them from getting clogged with, say, a virus?