In the last years, many studies (e.g. projects of the “NanoCare-Cluster”) have shown that ultrafine particles (less than 100 nm in diameter) and nanoparticles can be harmful for human health, especially if they are inhaled. Adverse effects of such particles also play a significant role in technical processes like the clean production of semiconductor devices. Therefore, the filtration of these airborne particles is both of health and of commercial interest.
This study presents experimental results of nanoparticle penetration though new and dust-loaded – in order to simulate real life application – filter media for particles with diameters between 5 nm and 500 nm. It is well-known that filtration efficiency for particles larger than 100 nm increases with an increasing amount of precipitated dust on filter media, whereas little is known about the behaviour of smaller particles. Therefore, we investigated this effect in particular for nanoparticles. In addition, we measured the deposition of electrically charged and uncharged nanoparticles onto charged and uncharged filters and compared the results with those for larger particles.
Figure 1 shows a schematic diagram of the experimental setup. A spark generator was used for silver or copper particles in the size range of 5 nm to 50 nm and an atomizer to disperse di(2-ethylhexyl) sebacate (DEHS) or a DEHS + isopropyl alcohol (IPA) mixture for the particle range of 50 nm to 500 nm. The test aerosol entered an electrostatic classifier, which was composed of an impactor, soft X-ray-neutralizer and differential mobility analyzer. The number concentrations of the unipolar monomobile particle fractions were measured upstream and downstream of the investigated filter media with two simultaneously used condensation particle counters (CPC). Depending on the purpose of the measurement, the particle fractions can either be neutralized by passing them through another neutralizer or left charged before they are counted or deposited on the sample, respectively.
The samples were loaded with Arizona fine dust (A2) by using a rotating brush generator (RBG). The dust was steadily applied with a mass concentration of 70 mg/m³ until the samples were loaded with 25 g/m² and 50 g/m² A2 (first and second loading stage, respectively). Filter efficiency and pressure drop were measured before and after loading.
To discharge the electrically charged synthetic filter media, they were dipped into IPA and dried at standard conditions afterwards. Figure 2 shows a result of this procedure with regard to the filtration efficiency...
....The experimental setup will be presented and the results of different samples with different properties discussed – particularly with regard to nanoparticle filtration.
Session: G10 - Short Oral + Poster Presentations I
Day: 14 March 2018
Time: 14:45 - 16:45 h