A new breakthrough could help people in Bangladesh whose water is tainted by arsenic from the Ganges River basin. Arsenic binds to iron oxides, and researchers at Rice University have found that hand-held magnets can remove nanoparticles of magnetite--an iron oxide--from water. By mixing the magnetite into contaminated water, a magnet can thus be used to remove both compounds. The researchers are now working on scaling up the procedure and discovering how to use cheaper iron oxides, such as those found in rust, so the method can be used in developing countries.

Source: Nikhil Swaminathan. Scientific American, November 9, 2006.