An all-protein aerogel with a nanofiber/foam structure for versatile air filtration

Structural design plays a vital role in advancement of multifunctional air filters. We here report a novel design of an all-protein aerogel with a unique hybrid nanofiber/foam structure, demonstrating versatile filtration capabilities, i.e. being able to capture oils & organic chemicals, toxic gaseous molecules, and particulate matter (PM), at a low pressure drop. The aerogel is made from two abundant natural proteins: zein and gelatin, by freeze-drying. The electrospun zein nanofibers dispersed within the hybrid zein/gelatin aerogel provide a large specific surface area and hydrophobicity, enabling high filtration efficiency even under a humid environment. The gelatin foam structure constructs a skeleton of the hybrid aerogel, extending the filtration capacities for capturing air pollutants. In addition, the optimal Z1/G1-3 aerogel sample exhibits high filtration efficiency of 99.24 % for PM2.5 and 95.54 % for PM0.3 at a low pressure drop of 54.76 Pa. More significantly, the Z1/G1-3 air filter presents exceptional filtration performance even when subjected to a high airflow rate of 10 L/min or after a continuous 120-min filtration period. This work proposes a novel air filter design that integrates eco-friendliness and multifunctional filtration features.