Trapping Wide Range of Pollutants with New Air Filter

Current air filters cannot simultaneously catch microscopic particles and toxic chemicals like formaldehyde, but now, an air filter from corn protein could.

Trapping Wide Range of Pollutants with New Air Filter
A layer of smog blankets Salt Lake City in early winter. Image Credit: Salil Bhatt on iStock

Enhanced air purifiers could be developed due to new research, particularly in areas with extremely low air quality. Engineers from Washington State University published a study in the journal Separation and Purification Technology on the design and material testing for this bio-based filter.

Particulate matter is not that challenging to filter but to simultaneously capture various kinds of chemical gas molecules, that is more significant. These protein-based air filtering materials should be very promising to capture multiple species of air pollutants.

Katie Zhong, Study Corresponding Author and Professor, School of Mechanical and Materials Engineering, Washington State University

Diseases including lung cancer, heart disease, and asthma are all influenced by poor air quality. Commercial air purifiers remove the microscopic soot, smoke, or exhaust particles that can be inhaled directly into the lungs, but air pollution frequently contains more dangerous gaseous molecules, including formaldehyde, carbon monoxide, and other volatile organic compounds.

High-efficiency particulate air filters, or HEPA filters, can catch microscopic particles but not gaseous molecules since they have pores with a diameter of a few microns. They are often composed of glass and petroleum-based products, which cause secondary pollution when used filters are discarded, according to Zhong.

The WSU researchers created an environmentally sustainable air filter from corn protein fibers that could simultaneously capture 99.5% of small particulate matter, similar to commercial HEPA filters and 87% of formaldehyde, which is higher than air filters made specifically for those types of toxins.

Corn was the agricultural product of choice for the researchers since it is widely available in the United States. The hydrophobic property of corn protein implies that it repels water which could be useful in a moist environment, such as a mask.

Functional groups refer to the amino acids in the corn protein. These functional groups operate as multiple hands that capture the toxic chemical molecules when they are exposed to the protein surface. By exposing a functional group at the protein surface, where it adsorbs formaldehyde, the researchers were able to show this.

They postulate that additional protein rearrangements could result in the development of a tentacle-like collection of functional groups that could seize a wide range of chemicals from the atmosphere.

Zhong added, “From the mechanism, it is very reasonable to expect that this protein-based air filter could capture more species of toxic chemical molecules.

Also, the three-dimensional structure they created exhibited great promise for a simple manufacturing process than the previous study team’s thin protein films. To connect the nanofibers into a thin, foam-like material, they employed a little amount of the chemical polyvinyl alcohol.

This work provides a new route to fabricating environmentally friendly and multi-functional air filters made from abundant natural biomass. I believe this technology is very important for people’s health and our environment, and it should be commercialized,” Zhong further added.

The scientists want to do more tests, making use of other functional group structures and other toxic chemical molecules. The study was carried out by graduate student Shengnan Lin, post-doctoral fellow Xuewei Fu, Ming Luo, Flaherty assistant professor at the WSU School of Mechanical and Materials Engineering, in addition to Zhong. The study was supported by a US Department of Agriculture Sun Grant.

Journal Reference:

Lin, S., et al. (2023) A protein aerogel with distinctive filtration capabilities for formaldehyde and particulate pollutants. Separation and Purification Technology. doi:10.1016/j.seppur.2023.123179.


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