The formation of ultrafine polyamide 6 nanofiber membranes with needleless electrospinning for air filtration

Particulate matter (PM) is a major air pollutant, which has a significant impact on public health. Filtration of PM through filters is a common method to protect the environment. However, the effective removal of PM with conventional filters still remains a challenge because of its small sizes. Here, we reported the formation of ultrafine polyamide 6 (PA-6) nanofiber membranes formed with needleless electrospinning, in which both relative humidity condition and electrode type were included in the discussion. The PA-6S nanofibers formed by using spiral electrode as a spinneret at 60% RH had the diameter of 33 nm, while the PA-6C nanofibers formed by using cylindrical electrode had the diameter of 120 nm. With the integration of fine diameter, small pore size, and high porosity, the resultant PA-6S nanofiber membrane exhibits high filtration efficiency of 99.42% and low pressure drop of 85.5 Pa under a face velocity of 85 L/min. Besides, it took only 10 minutes to reduce the concentration of PM2.5 from 999 to 34.1 mu g/m(3) when used to filter real PM particles.