Have Nanostructured Filters Been Developed Further?

Back in 2016, there was a potential breakthrough in air pollution reduction – specifically within the shipping industry. Start-up company Daphne Technology launched with the aim to use nanostructured filters to reduce levels of sulphur and nitrogen oxides emitted by large shipping vessels.

It was a much-needed development, with cargo ships emitting 204 times more sulphur than all of the cars in the world put together. But has the nanostructure technology been developed any further?

Silver catalyst

While the shipping filters are still in progress, there have been some pioneering uses of nanostructured filters elsewhere. Since the initial idea, chemists at the Tennessee State University (TSU) have begun developing a silver catalyst which functions as a nanostructured filter.

Catalysts are substances that can facilitate chemical processes without transforming themselves. Silver’s unique chemical make-up makes it suitable for decomposing carbon monoxide and formaldehyde amongst other toxic substances.

How does it work?

“Silver catalysts are less studied than other catalysts made with particles of precious metals—gold, platinum, and palladium. However, they can be just as effective in the oxidation of harmful volatile substances and cheaper by a factor of 10,” explained Gregory Mamontov, from TSU’s Laboratory of Catalytic Research.

TSU’s team of chemists have developed the catalyst using a uniquely produced silica gel. SBA-15, made up of nanotubes 6-10 nanometres in diameter, is used a base for the catalyst. Inside the nanotubes, a synthesis of cerium oxide and silver particles is conducted below 3 nanometres.

It is this synthesis that creates the catalytic activity. “Special interactions” within the nanotubes are activated by the harmful substances. It may even be possible to obtain the catalyst in powder or granular form, meaning it can be used in domestic air cleaning devices. And because it is stable at room temperature, there is no need to heat it – like some other products.

A more general use

So while Daphne Technology were focusing on the shipping industry, TSU’s catalyst is likely to be used more generally. Mamontov states the catalyst “will be in demand in industrial areas and cities to fight industrial emissions and smog from forest fires, which also contains a large amount of carbon monoxide.”

He adds that “the catalyst can be adapted to neutralize the gas discharges of chemical plants and the exhaust systems of automobiles.” Similar technologies have been developed in the past to capture harmful substances. ‘Big Market for Chemicals to Capture Mercury’ explores the industry reaction to new standards limiting discharges of mercury.