by Hilary Jones
ADELAIDE: A new air purifier using sunlight and nanoparticles has been created to clean up dangerous pollutants – called volatile organic compounds - in the air of our offices and homes.
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| All kinds of indoor furnishings, including carpet, can give off volatile organic compounds. |
The nanomaterial could be used in air purifiers, or even be coated onto walls and windows, according the to research presented today as part of a showcase of young Australian scientists at the Australian Cooperative Research Centres national conference in Adelaide.
Fumes given off from common indoors items – including paint, photocopiers, office furnishings, carpet and plastics – contain volatile organic compounds (VOCs). Common VOCs are formaldehyde, benzene and toluene.
Some are highly toxic
“Some of these compounds are highly toxic and can cause carcinoma,” said Ruh Ullah, doctoral student in the Department of Chemical Engineering at Curtin University in Western Australia.
The material contains nanoparticles of metal oxides, which, in the presence of light, water and oxygen, form hydroxyl radicals. These highly reactive radicals break down the VOCs in a reaction is called photocatalysis – producing harmless carbon dioxide, water and mineral salts.
“Contact between the VOCs and nanomaterials is very important for the reaction, so that’s why we used nanomaterials for enhanced surface area,” said Ullah.
Breaking down up to 77% of toluene
Ullah trialled nanoparticles created from common earth-based elements, such as silver, cobalt and tungsten, and from rare elements, such as tantalum, indium and niobium.
Tantalum oxide with added nitrogen is their best performing nanomaterial – it can break down up to 77% of toluene in a gas sample.
“Titanium dioxide is the most common nanomaterial currently commercially available, but it doesn’t work under light from fluorescent bulbs,” he said. The titanium dioxide works best under UV light – it does not work under indoor lighting and only removes 5% of VOCs under sunlight.
Coming to an office near you
“The material we have prepared is capable of working under fluorescent light, and outside it can remove up to 77% of volatile organic compounds,” he said. Under indoor lighting, the new tantalum compound can remove up to 30% of VOCs and can be reused multiple times, unlike the titanium which is single-use.
Most current filters effective against VOCs require high temperature and pressures and use a lot of en energy, so they are not practical for public and residential spaces, according the researchers. Volatile organic compounds make up 31% of indoor air pollution in workplaces and homes.
“The volatile organic compounds have a more severe effect in an indoor environment, as compared to an outdoor environment, and nowadays people spend more than 90% of their time indoors,” said Ullah.
“VOCs are often implicated in sick building syndrome when workers experience persistent ill-health, estimated to cost the Australian economy over $12 billion a year.”
The research is conducted with the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, which plans to liaise with industry to commercialise the research.
“We expect that the technology will be implemented in the next a few years,” said Shaobin Wang, the leader of the project at Curtin University.
Fonte: Cosmos
