Building a Tailored Frame-Channel Structure for High-Performance Protein Air Filters.

To create a healthier indoor environment via sustainable technologies, there is a growing demand for constructing high-performance air filters from natural materials. Addressing this need, we have fabricated high-performance protein air filters with a tailored frame-channel structure via electrospinning. The innovative feature of the protein air filter is generated by adding a small amount of an organic salt, tetrabutylammonium chloride (TBAC), to modulate the denaturation of zein for tuning electrical charge distribution and hydrophilicity of the protein solutions. The results highlight that the optimized filter with 1.0 wt% TBAC exhibits a denser nanofiber assembly on the frame and a sparser arrangement on the channel. Functionally, the filter demonstrates ultralow pressure drop (ca. 9.04 Pa) that is only a third of that observed in unmodified formulation and commercial air filters, while it maintains high filtration efficiency in capturing PM2.5 (99.42% ± 0.30%) and PM0.3 (98.25 ± 0.39%). More importantly, the filter indicates multifunctional perspectives, e.g., high removal efficiency for formaldehyde (HCHO) and PM2.5 under high airflow rates (up to 8 L/min) or after prolonged testing period (120 min). Our design of the frame-channel structure for the protein air filter marks a leap forward in developing biomass-based structural materials.