The use of filters to control air quality has been implemented widely in all types of structures. Unfortunately, filters risk becoming platforms for the growth of bacteria, which can then be dispersed further in the air stream. To combat this, antibacterial materials are being incorporated into filter media. In this work, we tested two routes for introducing nanoscale silver into filters containing activated carbon fibers (ACF): first, by adding silver nanofibers directly to the fiber fabrication process and second, by coating a pre-existing filter with silver nanoparticles generated by a liquid flame spray (LFS). The resultant filters were evaluated for methanol adsorption, particle penetration and antibacterial activity. The results show that both methods are suitable for producing antibacterial filters as well as being highly tailorable and scalable for specific needs.

We investigated the capturing mechanisms of highly charged macromolecular ions of polyethylene glycol electrosprayed onto a metal screen. Our experiments assessed how the charge state, size of the macromolecular ions, and filtration velocity affected the penetration of the ions through the metal screen. The single fiber efficiencies were plotted as functions of the Peclet number and image force parameter. Highly charged molecular ions had much higher collection efficiencies than neutralized macromolecules, suggesting the presence of a strong image force between the ions and metal surface. The single fiber efficiency by image force was proportional to the square root of an image force parameter predicted by theory. When using the prefactor of 9.7 proposed by Alonso et al. (2007), we found fair agreement between the experimental data and theoretical predictions on the collection efficiency of highly charged molecular ions with mobility diameters from 2.6 to 4.8 nm and numbers of electrical charges from 2 to 7. The experimental evidence from our study reveals that image force contributes strongly to the collection of multicharged macromolecular ions by a metal wire screen.

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