by Staff Writers
Pullman WA (SPX) Jan 17, 2017
Washington State University researchers have developed a soy-based air filter that can capture toxic chemicals, such as carbon monoxide and formaldehyde, which current air filters can't.
The research could lead to better air purifiers, particularly in regions of the world that suffer from very poor air quality. The engineers have designed and tested the materials for the bio-based filter and report on their work in the journal Composites Science and Technology.
Working with researchers from the University of Science and Technology Beijing, the WSU team, including Weihong (Katie) Zhong, professor in the School of Mechanical and Materials Engineering, and graduate student Hamid Souzandeh, used a pure soy protein along with bacterial cellulose for an all-natural, biodegradable, inexpensive air filter.
Hazardous gases escape most filters
With many sources of pollution in some parts of the world, however, air pollution also can contain a mix of hazardous gaseous molecules, such as carbon monoxide, formaldehyde, sulfur dioxide and other volatile organic compounds.
Typical air filters, which are usually made of micron-sized fibers of synthetic plastics, physically filter the small particles but aren't able to chemically capture gaseous molecules. Furthermore, they're most often made of glass and petroleum products, which leads to secondary pollution, Zhong said.
Soy captures nearly all pollutants
Soy contains a large number of functional chemical groups - it includes 18 types of amino groups. Each of the chemical groups has the potential to capture passing pollution at the molecular level. The researchers used an acrylic acid treatment to disentangle the very rigid soy protein, so that the chemical groups can be more exposed to the pollutants.
The resulting filter was able to remove nearly all of the small particles as well as chemical pollutants, said Zhong.
Filters are economical, biodegradable
"We can take advantage from those chemical groups to grab the toxics in the air," Zhong said.
The materials are also cost-effective and biodegradable. Soybeans are among the most abundant plants in the world, she added.
Zhong occasionally visits her native China and has personally experienced the heavy pollution in Beijing as sunny skies turn to gray smog within a few days.
"Air pollution is a very serious health issue," she said. "If we can improve indoor air quality, it would help a lot of people."
Patents filed on filters, paper towels
The work is in keeping with WSU's Grand Challenges, a suite of research initiatives aimed at large societal issues. It is particularly relevant to the challenge of sustaining health and its theme of healthy communities and interventions to sustain public health.
Washington State University
Our Polluted World and Cleaning It Up