Chemistry hits the catwalk

Catalytic Clothing - The jeans that remove air pollutants.
13 February 2018

Interview with 

Tony Ryan, University of Sheffield


Person wearing jeans standing next to a car


It’s time for science to hit the catwalk. One project called Catalytic Clothing is adding nanoparticles to our attire. These extremely small particles stick to the fabric fibres undergoing a series of chemical reactions to create a very reactive molecule - called a radical - that breaks down air pollution. Georgia Mills spoke to founder and Physical Chemist, Tony Ryan from University of Sheffield, to hear more about the project.

Tony - What we’ve done is make a technology work with clothing such that people can be perambulating environmental cleanup agents. We can make people wander around in their clothes, cleaning up.

Georgia - How does that work?

Tony - There are reports in the newspapers regularly about a) the level of pollution, and b) the effect it has on human health. The invisible killer in terms of air pollution is nitric oxide. Nitric oxide is a lung irritant, but if you convert it into the acid or the nitrate it becomes water soluble and it washes out of the air.

Georgia - Is this what your material does?

Tony - Yeah. It’s exactly what it does. What we’ve done is put some tiny particles - nanoparticles of titanium dioxide, titania - on clothes. The nanoparticles sit on the fabric, the sunlight hits them. It splits oxygen molecules, they react with water to make this hydroxyl radical. Then the hydroxyl radical reacts with the nitrous oxide to make nitric acid which is then soluble in the water vapour that’s in the air. The great thing is because your kind of hot and damp, so the particles are bathed in warm damp air, the particles deal with the pollution and then your physiology carries it away.

Georgia - How would it work in practice? How would you convert a piece of clothing? Say I wanted a nice hat that did this, how would we go about making it work?

Tony - I have a couple of pairs of catalysed jeans and some catalysed tee shirts and we do it in the lab by using a spray, like a diffuser spray that you’d use to water plants. We put a solution of nanoparticles into a hand spray device and then literally just spray the clothes, and when the water evaporates the nanoparticles are left on the clothes.

To do it at scale, what we’d like to be able to do is present the technology in the laundry detergent or in fabric conditioner because this fantastic chemistry goes on in the washing machine and you’d be able to wash it into your clothes.

Georgia - Okay. I’ve got my catalytic hat. How much of an effect will this have on the air around me?

Tony - What I’d need to know to tell you that is how much the hat weighs? Then that allows me to calculate its surface area because I know the diameter of the fibres. Once I know its total surface area, then I can work out what the loading is of the nanoparticles, and then I can calculate how much nitric oxide it would take out. I know the numbers off by heart for a pair of jeans.

Georgia - Okay. Let’s go with jeans then to make life easy.

Tony - A pair of jeans would take out about 5 grams of nitric oxide. The average car produces about 12 grams of nitric oxide in a day so a pair of jeans takes out the pollution from half a car. If everybody in London wore one item of catalytic clothing, then you’d be able to remove about half of the nitric oxide burden on London.

Georgia - Oh wow! I know London frequently goes over its limits for the year within about the first couple of months, doesn’t it?

Tony - Yeah. It already went over the limit in January for the whole year.

Georgia - Woops!

Tony - Yeah. Woops indeed!

Georgia - What’s the catch. This sounds like a great idea so what are you hoping is going to happen next?

Tony - We’ve not quite got to market. There’s a couple of frightening things for people: the first is the word nanoparticle; the second is the nanoparticles can’t tell the difference between a good smell and a bad smell. For example, not only will they oxidise body odour, and another that the particles will oxidise you know as perfume. We produced some tee shirts for a literary festival and all the stewards wore these tee shirts. I asked them had they noticed anything and they said well, yeah, they stay clean. You can spill tomato ketchup on catalytic clothing and it will disappear in a day or so. But, a young lady said “my perfume just goes”, and I was delighted to hear that because it meant the technology was working. But it also means that laundry companies who basically sell the idea of freshness as a fragrance, lose that fragrance if they have technology in the washing powder that cleans up pollution.

Georgia - I see. Does wearing one of these pieces of clothing directly benefit you or is it more the city you live in?

Tony - Therein lies a problem for marketing. No, you don’t get a benefit from your wearing of catalytic clothing. I guess, unless you walk down the street backwards. But everybody else does because you leave a trail of cleaner air behind you so it’s more of a herd immunity affect. If everyone wore catalytic clothing we’d all benefit, but if one individual wears catalytic clothing there’s hardly any difference.

Georgia - Are there any other applications you could have for this particle?

Tony - One of the things we did was it works on any fabric. It worked really really well on posters and at the literary festival where I found out that the perfume was taken away, I spoke to Simon Armitage, the poet, and he was so inspired by what I told him that he wrote a poem called In Praise of Air. We had that printed on a 20 metre by 30 metre banner that went up on one of the buildings at the University of Sheffield and that took out the pollution from about ten cars a day. You see flags all over cities and this technology works really really well in the urban environment. We have been working with advertising companies around putting catalytic air pollution solutions onto advertising awnings.

Georgia - I suppose you’d be an advocate for art and science working together then?

Tony - Completely and utterly an advocate for art and science working together. My research has been improved by my collaboration with artists, and we’ve been able to do some inspiring art that makes people think about their environment and how they live their lives.


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