Powder to quickly disinfect water in 60 seconds

In tests, the new powder quickly purified a 200-ml glass of water contaminated with about one million E. coli bacteria per ml.

New water purification powder could be used by hikers who need to get water from streams and lakes. Photo: Depositphoto — New water purification powder could be used by hikers who need to get water from streams and lakes. Photo: *Depositphoto*

If you place a clear water bottle in sunlight, the ultraviolet rays will kill harmful bacteria inside, making the water drinkable. However, the bottle must be exposed to sunlight for at least 6 hours. A team of scientists from Stanford University and the SLAC National Accelerator Laboratory has developed a new powder that is activated by sunlight and can purify water in just 60 seconds. The new research was published in the journal Nature Water on May 18.

The new powder is made from nano-sized pieces of aluminum oxide, molybdenum sulfide, iron oxide, and copper. These materials are readily available and inexpensive. In addition, only a small amount of the powder is needed to treat a relatively large amount of water.

First, mix some of the powder with dirty water in a clear bottle or jar, then expose the jar to direct sunlight. The molybdenum sulfide and copper absorb photons from the light, then act as semiconductors that allow the photons to release electrons. These free electrons react with water, creating hydroxyl radicals and hydrogen peroxide that kill bacteria by breaking down their outer protective membranes.

Once the filtration process is complete, the remaining hydroxyl radicals and hydrogen peroxide quickly break down into water and oxygen, making the water safe to drink. Because it contains iron oxide, the nano-slices can be collected for reuse by dipping a magnet through the water.

In their tests, the team added a small amount of the powder to a 200-ml glass beaker, which was contaminated with about a million E. coli bacteria per ml at room temperature. After placing the beaker in natural sunlight for 60 seconds, they found no surviving bacteria. Another advantage is that the powder can be reused an additional 30 times.

Scientists hope the new technology will be used in underdeveloped areas that lack water filtration infrastructure, or for hikers who need to collect water from streams and lakes. The new powder could even be useful in water treatment plants, which currently use artificial ultraviolet light to kill bacteria.

"During the day, the plant can use visible sunlight, which works much faster than ultraviolet light and also saves energy. The nanoflakes are quite easy to make and can be quickly multiplied by the ton," said Yi Cui, a professor at Stanford University and a member of the research team.

Thu Thao (According to New Atlas )

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