Silver nanoparticles provide clean water for $2 a year

[Nipuna]

SOMETIMES the solution to an enormous problem is tiny. Silver nanoparticles may be the key to supplying clean, affordable drinking water worldwide.

Thalappil Pradeep at the Indian Institute of Technology in Chennai and colleagues have developed a filter based on an aluminium composite, embedded with silver nanoparticles. As water flows through the filter, the nanoparticles are oxidised and release ions, which kill viruses and bacteria, and neutralise toxic chemicals such as lead and arsenic.

Some nanoparticles leach into the water but at concentrations that pose no threat to health. Pradeep describes the process of making the filter as "water positive": 1 litre of water spent on making nanoparticles gives 500 litres of clean water.

In tests, a 50-gram composite filtered 1500 litres of water without needing reactivation, so they estimate that a 120g-filter that costs just $2 would provide safe drinking water for a family of five for one year (PNAS, DOI: 10.1073/pnas.1220222110).

The filters are undergoing field trials in India with the aim of preventing waterborne diseases.