A Disposable Multi-Functional Air Filter: Paper Towel/Protein Nanofibers with Gradient Porous Structures for Capturing Pollutants of Broad Species and Sizes

Highly polluted air is usually concentrated with particles of broad sizes and species of gaseous toxic chemicals. Filtration of these pollutants simply relying on size effects is not sufficient; instead, strong interactions between filtering materials and pollutants are in critical need. Moreover, to reduce or even avoid further pollution to the environment from disposing of the massive amount of used air filters demands the development of "green" air filtering materials. Here, we report a high-performance hybrid cellulose/protein air filter with nanofiber structures. Interestingly, it was discovered that textured cellulose paper towel can not only act as a flexible mechanical support but also as a type of air flow regulator that can improve pollutant–nanofilter interactions. Therefore, the high-performance natural protein-based nanofabrics are promoted both mechanically and functionally by textured cellulose paper towel. Study results indicate that this hybrid filtering material possesses excellent removal efficiency for particulate matter with a broad size range, in particular for small pollutants, the most challenging for air filtration, and multiple species of toxic chemicals. This study indicates that the protein/cellulose hybrid system can be used in high-performance air filters and are disposable due to the abundance and environmental friendliness of the original materials.