A protein aerogel with distinctive filtration capabilities for formaldehyde and particulate pollutants

Natural protein air filters are not only promising to resolve environmental issues caused by petroleum-based materials, but also may display multi-functional filtration capabilities. To achieve the high filtration performance, there is a pressing need to rationally design the architecture of the filtering materials. In this study, zein (corn protein) nanofibrous aerogels (ZNAs) with controlled structures are fabricated for effectively capturing particulate matter (PM) and gaseous toxic chemicals (such as formaldehyde (HCHO)). Small amount of polyvinyl alcohol (PVA, 0.5–2.0 wt%) is added to “glue” dispersed zein nanofibers to form the 3D network aerogels. It is revealed that all the ZNA samples exhibit excellent efficiencies for capturing both particulate matter (PM) and HCHO (up to 89.75%), and the one with 1.5 wt% PVA (ZNA-1.5) presents the optimal filtration performances including filtering 98.80% of PM0.3 and 99.52% of PM2.5 as well as 87.41% of HCHO at a low pressure drop. Furthermore, filtration performances for both HCHO and PM2.5 of ZNA-1.5 are also very distinctive in comparison with that of typical commercial filters as well as reported bio and non-bio filters. Significantly, ZNA-1.5 delivers the similar high efficiency of PM2.5 to that of high efficiency particulate air filter (HEPA) as well as higher HCHO efficiency than commercial activated carbon air filter, a specially designed chemical air filter for capturing toxic chemicals in air. This work provides a new route to fabricating environmental-friendly and multi-functional air filters made of abundant natural biomass for broad applications.