Filters with Nanofibers

The effectiveness of ineorporating a nanofiber layer on conventional filter media has been reeognized for some time in the air filter industry. Typically, these applieations have been for dust removal and the media has demonstrated robustness for a wide range of applications. Industry leaders such as Donaldson Company (Minneapolis, MN 55431) routinely manufae-ture air filters with a nanofiber eomponent in them (Graham et al. 2002). Nanofibers are ineluded in commereial filters to serve two purposes  

When applied as a thin layer over eonventional media nanofibers enhance their filtration efficiency. 

The solidity (ratiier than its overall thickness) is a key parameter defining efficiency of a filter. Increasing file solidity of the filter results in an increase in the pressure drop as the drag increases, and also an increase in 

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Leung WWF, Hung CH, Yuen PT (2010) Effect of face velocity, nanofiber packing density and thickness on filtration performance of filters with nanofibers coated on a substrate. Sep Purif Technol 71(l) 30-37. doi 10.1016/j.seppur.2009.10.017... 

Electrospinning is a process utilized by the nanofiltration process, in which fibers are stretched and elongated down to a diameter of about 10 nm. The modified nanofibers that are produced are particularly useful in the filtration process as an ultra-concentrated filter with a very large surface area. Studies have found that electrospun nanofibers can capture metallic ions and are continually effective through re-filtration. 

Cho D, Naydich A, Frey MW, Joo YL (2013) Further improvement of air filtration efficiency of cellulose filters coated with nanofibers via inclusion of electrostatically active nanoptuticles. Polymer 54(9) 2364-2372, http //dx.doi.Org/10.1016/j.polymer.2013.02.034... 

WangJ, Kim SC, Pui DYH Investigation of the figure of merit for filters with a single nanofiber layer on a substrate,/ Aerosol Sci 34 323—334, 2008. 

These nanofilters are reusable filters that have controlled porosity at the nanoscale and at the same time, can be formed into macroscopic structures with controlled geometric shapes, density, and dimensions. A carbonaceous nanofilter was fabricated by carbon nanofiber, in the best condition was used for MS2 virus removal. The results showed that at pressures of 8-11 bar the MS2 viruses were removed with a high efficiency by using the fabricated nanofilter. The results showed that the fabricated nanofilter... 

FIGURE 9.12 Illustration of the elution head-based TLC-MS Interface (a) and layer imprints on the backside of a PAN nanofiber layer after elution (b). Modified use of the interface with filter paper between the elution head and the monolithic silica UTLC plate to avoid leakage of the elution solvent (c). (Reprinted from Kampalanonwat, P., Supaphol, R, and Morlock, G.E., J. Chromatogr. A, 1299,110-117,2011 Vovk, I. et al., J. Chromatogr. A, 1218, 3089-3094, 2013. Copyright 2011 and 2013, with permission from Elsevier.)... 

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