Nanoparticle filtration by electrospun polymer fibers

Polyacrylonitrile (PAN) fibers with mean diameters in 270-400 nm range were prepared by electrospinning for use as a filter media. Compared to commercial filters made of polyolefin and glass, the fibers of electrospun filters were more uniform in diameter. The performance of electrospun filters was evaluated by measuring the penetration of monodisperse NaCl nanoparticles (below 80 nm in size) through the filters. It was found that electrospun filters could be made which had nanoparticle penetration values comparable to commercial filters but with substantially less filter mass. The penetration of nanoparticles through the electrospun filter media could be reduced by increasing the filter thickness, which is controlled by the collection time during the electrospinning process. Nanoparticle collection by electrostatic forces was found to be negligible for electrospun filters. Filter quality factors and single fiber collection efficiencies were found to be independent of filter thickness for electrospun filters, and the penetration of nanoparticles through electrospun filters was in better agreement with theoretical predictions than was the measured penetration through a commercial filter. This study shows that electrospinning is a promising technology for the production of high performance nanoparticle filters.