Large-scale blow spinning of heat-resistant nanofibrous air filters

Particulate matter (PM) pollution has become a serious problem worldwide and various kinds of nanofibrous filters aiming to solve the problem have been developed. It is urgent to remove PM from high-temperature pollution sources, such as industrial emissions, coal furnaces, and automobile exhaust gases. However, filtration at pollution sources remains challenging because most existing air filters are not resistant to high temperature. Herein, heat-resistant polyimide (PI) nanofibrous air filters are fabricated via a simple and scalable solution blow-spinning method. These air filters show excellent thermal stability at high temperature up to 420 °C. They exhibit a filtration efficiency as high as 99.73% at ambient temperature and over 97% at 300 °C. In addition, a field test shows that the filters remove > 97% of PM from the car exhaust fumes. Hence, the blow-spun PI nanofibrous membranes combined with the facile preparation strategy have great potential in high temperature air filtration fields and other similar applications such as water purification and protein separation.