A soy-based air filter that may be more effective at capturing toxic chemicals than conventional filters has been developed by researchers at Washington State University. The bio-based filter could lead to better air purifiers, particularly in regions of the world that suffer from poor air quality.

The inexpensive, biodegradable air filter consists of pure soy protein and bacterial cellulose.

Soy filter before and after use.Soy filter before and after use.Conventional air filters, typically made of micron-sized plastic fibers, physically filter small particles of pollutants. They often are unable to chemically capture toxic gaseous molecules such as carbon monoxide, formaldehyde, sulfur dioxide, and other volatile organic compounds that contaminate the air in many parts of the world, researchers say.

Moreover, commercial filters are most often made of glass and petroleum products, which leads to secondary pollution, they say.

The soy-based nanofiber filter developed by WSU researchers and their Chinese counterparts at the University of Science and Technology Beijing contains several functional chemical groups, including 18 types of amino groups, each capable of capturing passing pollution at the molecular level.

The researchers used an acrylic acid treatment to disentangle the rigid soy protein so that the chemical groups can be more exposed to the pollutants. Tests showed the resulting filter was able to remove nearly all small particles as well as chemical pollutants, say lead researcher Weihong (Katie) Zhong, a WSU professor in the School of Mechanical and Materials Engineering.

The materials that make up the filter, especially soybeans, are inexpensive and abundant, which researchers hope will help encourage its commercialization, particularly in countries plagued by poor air quality such as China.

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