As well as generating renewable energy, wind turbines might soon remove air pollution too.
Zhong Lin Wang at the Georgia Institute of Technology in Atlanta and his colleagues have developed a wind-powered device that can simultaneously absorb and break down air pollutants.
It resembles a horizontal wind turbine with five 25-centimetre diameter transparent hemispheres at the end of arms that act as cup-like blades. These also funnel air to a water-filled chamber where nitrogen oxide gases dissolve to produce nitrate and nitrite ions.
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These gases, which are found in vehicle emissions and are released by the burning of fossil fuels, can be harmful. They include nitric oxide and nitrogen dioxide, which contribute to smog and acid rain.
The device is powered by multiple generators that convert the mechanical energy of the moving blades into electricity.
The turning of the blades causes generators in the turbine to produce electrical current that is used to power electrochemical reactions involving the nitrate and nitrite ions. In the process, these substances are converted to other compounds such as ammonia and nitrogen and stored. Nickel foam – a solid form of the metal that is porous – is used as a catalyst.
The researchers found that the device could effectively degrade nitrogen oxides when turned by a fan that creates a wind speed of 6 metres per second. They tested it for 24 hours and found a significant reduction in the concentration of nitrite ions in the water-filled chamber, and an increase in ammonia gas, which is captured in a chamber.
The team suggests that the turbines could be useful in cities – for example, by fitting them to the top of street lights to remove air pollution.
Journal reference: ACS Nano, 10.1021/acsnano.9b08496
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