Rising alarm over the impact of indoor air pollution on Australia's health and rate of lung disease has sparked a national research effort to develop new ways to remove toxic substances from the air of homes, offices and factories.
Researchers in the Cooperative Research Centre for Contamination Assessment and Remediation Technology (CRC CARE) at Curtin University of Technology are using nanotechnology to develop two world-first methods of filtering cancer- and disease-causing substances out of indoor air.
"Indoor air quality is attracting greater public attention due to its impact on health, which is estimated to cost Australia about $12 billion annually," project leader Professor Moses Tadé says. "Air toxics consist mainly of volatile organic compounds (VOCs), gas-like pollutants that can leak from sources such as paints, glues, coatings, pesticides, carpets, plastics, cleaning fluids and office equipment.”
Long-term exposure to VOCs causes sick building syndrome (SBS), in which the building's occupants experience rising levels of eye, nose and throat irritation, headache, allergic reactions, breathing difficulties, nausea, nosebleeds, vomiting, fatigue and dizziness.
"Australians typically spend up to 90 percent of their time indoors, breathing levels of air pollution which are often higher than those on a busy highway."
The solution, says Professor Tadé, is to develop ultra-efficient, low-cost technologies which can 'scrub' the VOCs from the surrounding air. His team is developing two innovative techniques based on nanomaterials.
The first is a combination of adsorption and catalytic destruction which uses a nanosized porous material with high adsorption capacity and catalytic activity to achieve low-temperature destruction of the toxic VOCs.
The second is known as photocatalytic oxidation (PCO) and uses a nanosized photocatalyst with visible light function to oxidise VOCs at room temperature, rendering the air safe for people to inhale.
The scientific challenge lies in the fact that, while substances with good filtration ability have been found, they generally require high temperatures to operate efficiently.
The goal is to use nanotechnology to create a 'molecular sieve' that will operate efficiently at low temperature, screening out and trapping the dangerous particles, and completely destroying VOCs. Nanotechnology works better at low temperature is that its particles are so small. This gives them superior ability to filter, adsorb and catalyse things like VOCs.
The second technology, PCO, promises to be cheaper than the molecular sieve, but there are research challenges to be overcome in developing a truly efficient catalyst that will soak up the VOCs using natural light as a stimulant for its semiconductors which normally use ultraviolet.
The new technologies could be incorporated into existing air conditioning systems or included as new catalytic or photolytic reaction modules in building design.