Low cost, portable filter can purify toxic water in minutes

Scientists have developed low cost, portable filters that can make water contaminated with heavy metals safe for drinking in a matter of minutes.

The technology could be put to good use in Africa and Asia in places where heavy metal ions in the water are at levels well beyond safe human consumption, researchers said.

It is estimated that 790 million people, or one in 10 of the Earth's population, do not have access to clean water.

There are portable filtration products available that do remove heavy metals from water, but they are comparatively expensive, often costing more than USD 100.

By contrast, the aluminium oxide filters produced developed by researchers from University of New South Wales and RMIT University in Australia could be produced for as little as 10 cents, making them attractive to prospective manufacturers.

Researchers said the manufacture process is so cheap and requiring such low expenditure of energy, these filters could even be made out of a kitchen.

In a study published in the journal Advanced Functional Materials, researchers showed that when a chunk of aluminium is added to the core of liquid gallium at room temperature, layers of aluminium oxide are quickly produced at the surface of the gallium.

These aluminium oxide nano-sheets were highly porous and were suitable for filtering both heavy metal ions and oil contamination at unprecedented, ultra-fast rates.

The low cost and portable filters produced by this new liquid metal based manufacturing process could be used by people without access to clean drinking water to remove substances like lead and other toxic metals in a matter of minutes, said Kourosh Kalantar-zadeh from University of New South Wales in the US.

"Lead and other heavy metals have a very high affinity to aluminium oxide. As the water passes through billions of layers, each one of these lead ions get attracted to one of these aluminium oxide sheets," said Kalantar-zadeh said.

"Because it's super porous, water passes through very rapidly. But at the same time, it's very safe because with repeated use, the water flow cannot detach the heavy metal ions from the aluminium oxide," he said.

"We are publishing this concept and releasing it to the public domain, so people around the world can use the idea for free and implement it for enhancing the quality of their lives," he said.