The saltwater is pushed between a pair electrodes: a silver electrode, which attracts chlorine ions, and an electrode made of manganese oxide nanorods, which attracts the sodium ions. To remove the ions from the electrodes, a separate stream of saltwater moves between the electrodes in the opposite direction.
Mauro Pasta and Fabio La Mantia of Ruhr University Bochum and Colin D. Wessells and Yi Cui of Stanford University wrote up the discovery in Nano Letters. The discovery comes out of previous research by Pasta, La Mantia, Cui, and Heather D. Deshazer of Stanford University and Bruce Logan of Penn State University to find sources of clean energy. In that research, saltwater of varying salinity was pushed between the electrodes to create an electric current.
Right now, the technology can remove 50% of the original salt in a single pass-through. Pushing the water through the battery several times removed more of the salt, but that takes energy. The researchers intend to improve on their discovery until a single pass-through creates potable water from seawater.
Potential in a Battery
The original paper is behind a paywall, so all the details aren’t available to me, but it seems like this battery holds a lot of potential.
If the water were pushed between the electrodes by a free source of energy, like the incoming tide, would it also create electricity at the same time? Even if it didn’t create energy, the ebb and flow of the tide would provide the energy needed to desalinate water and then clean the electrodes.
A series of batteries could desalinate the water more than 50%, or perhaps the partially desalinated seawater could then be wholly desalinated by another method. For instance, the electrodes could line an intake pipe for an already existing desalination plant and reduce the energy cost and time involved.
Of course, salt isn’t the only obstacle keeping us from drinking seawater, but this battery seems like a fine addition to current desalination technology.
Desalination plant on St. Martin photo via Shutterstock