Volume 15, No. 6, November 2015, Pages 2422-2435 PDF(3.56 MB)
Separation of Nanoparticles from Air Using Melt-Blown Filtering Media
Anna Jackiewicz, Łukasz Werner
Department of Chemical and Process Engineering, Warsaw University of Technology, Warsaw, Poland
- The melt-blown technique was used to produce filters for separating nanoaerosols.
- Solid and liquid polydisperse nanoparticles were separated from air.
- It was verified how the process conditions affect the nanofiltration efficiency.
- The influence of filter and particle morphology on nanofiltration was investigated.
- Experimental data were described by the classical theory and a complex model.
Over the last few years, expectations have grown for the development of appropriate materials for separation of nanoparticles of different morphologies from air. Therefore, the objective of this work was to conduct a broad study of the process of filtration of polydisperse nanoaerosols in materials of our design and production. They were made using the modified melt-blown technology, a very promising technique that allows to produce large amounts of fibers with a wide range of diameters which when properly formed in mats or cores can be used in various filtering products, such as protective masks, car filters. The filtration efficiency for KCl solid nanoparticles and DEHS (di-ethyl-hexyl-sebacat) liquid nanoparticles in three polypropylene filters of different morphologies have been established. The obtained results show how the aerosol face velocity and the morphology of the nonwoven media affect the filtration efficiency and pressure drop. It turned out that fibrous filters of our own production can separate particles with very small diameters from the air. As the effectiveness of the separation grew with a decrease in diameter of filter fibers, a filter composed of nanoscale fibers proved to be the most effective. An increase in aerosol flow velocity through the filter negatively affected its filtering effectiveness. The observation of data for cubical KCl and spherical DEHS particles, showed no differences in filtering effectiveness, which proves that for the tested diameter range the morphology of particles removed from air does not play a significant role, as it does for larger particles. The results obtained from the filtration of polydisperse nanoaerosols were successfully interpreted using our Partially Segregated Flow Model which takes into account the polydisperse distribution of fiber diameters in the filter. What is more, it shows that the application of the classical theory of filtration significantly overvalues the results obtained in our experiments.
Nanoparticle measurement; Filtration; Fabric filters; Aerosol deposition; Aerosol generation.