Exploration of Ultralight Nanofiber Aerogels as Particle Filters: Capacity and Efficiency.

Ultralight nanofiber aerogels or nanofiber sponges are a truly three-dimensional derivative of the intrinsically flat electrospun nanofiber mats or membranes. Here we investigated the potential of such materials for particle or aerosol filtration, since particle filtration is a major application of nanofiber mats. Ultralight nanofiber aerogels were synthesized from electrospun nanofibers using a solid templating technique. These materials had a tunable hierarchical cellular open pore structure. We observed high filtration efficiencies of up to 99.999 % at most penetrating particle size (MPPS). By tailoring the porosity of the nanofiber aerogels through the processing parameters, we were able to adjust the number of permeated particles by a factor of 1000 and pressure drop by a factor of 9, respectively. These nanofiber aerogels acted as a deep-bed filter and they were capable of handling high dust loadings without any indication for performance loss or increase in pressure drop. When increasing the face velocity from 0.75 to 6 cm s-1, filtration efficiency remained high within a factor of 1.1 to 10. Both characteristics were in contrast to the behavior of two commercial nanofiber mat particle filters, which showed significant increase in pressure drop with filtration time as well as a susceptibility against high face velocities by a factor of 105.