Squeezable Gel Delivers Clean Drinking Water

A cheap, lightweight material could one day help survivors of natural disasters get clean water fast. A porous gel embedded with silver nanoparticles absorbs contaminated water, kills bacteria in seconds, and releases drinkable water with a squeeze (Environ. Sci. Technol. 2013, DOI: 10.1021/es401219s). Xiao (Matthew) Hu, a materials scientist at Nanyang Technological University, in Singapore, and his colleagues synthesized the gel and used it to sop up water laced with two troublesome bacterial species, Escherichia coli and Bacillus subtilis. After 15 seconds, the amount of bacteria in the water squeezed out of the gel was 0.1% that of the original levels. When the team increased the soak time to five minutes, the amount of bacteria in the treated water was about one-millionth that of the tainted water. The team reports that a thin, 4-g cylinder of the material can soak up and purify a half-liter of water with one squeeze. The gel can be reused more than 20 times without degrading or losing its bactericidal powers.