Size-Resolved Penetration Through High-Efficiency Filter Media Typically Used for Aerosol Sampling

Abstract

We have developed a new, fully controlled filter testing device and have used it to measure size-resolved penetration through a typically used filtration media for (but not only) atmospheric aerosol sampling. Twenty membrane and fiber filter pieces (mixed cellulose ester filters, polytetrafluoroethylene filters, quartz fiber filters, glass fiber filters, and polycarbonate filters) of various manufacturers and filter codes were examined. High variability in the penetration curve shapes, most penetrating particle size (MPPS) (from 20 nm to 90 nm) and penetration maxima (from 0.001% to almost 100%) has been found. The dependence of pressure drop on face velocity generally agrees with theory, the comparison of penetration at various face velocities proved the theoretical equations being able to determine MPPS only partially correctly. Although the variability within an individual filter of the same code is not negligible, it is small compared to the differences between the various filter types. The results not only differed from the information provided by the manufacturers, but in many cases also provided information otherwise unavailable, although affecting the sampling and also the ability of comparison with theory. To have enough information for the proper choice of the filter for a given purpose, it would be necessary to have not only total penetration given from the DOP standard measurement, but the MPPS, penetration maximum value and pressure drop as well.

Chemical discrimination of the particulate and gas phases of miniCAST exhausts using a two-filter collection method

“…The minimum collection efficiency, which is also referred to as the most penetrating particle size (MPPS), is obtained for the 100-300 nm size range. However, some studies showed that the MPPS for QFF may peak around 60 nm and are possibly < 100 nm for other fibrous media (Brochot et al, 2019;Zíková et al, 2015). While this measured values are mostly influenced by both the flow velocity in the sampling line and the pressure drop at the surface of the filter, our flow conditions are close to those used in the work of Zíková et al (2015).…”

“…CC BY 4.0 License. efficient in capturing combustion emissions and they have a stable penetration curve among other filters when a range of physical parameters are varying in the sampling line (Zíková et al, 2015). From a theoretical point of view, it is very difficult to predict the collection efficiency of QFF for particles within the nanometer size domain, as generated in our combustion conditions (e.g.…”

“…99-166 nm modal diameter, Bescond et al, 2016). Filter collection efficiency is directly related to inertial impaction, direct interception, Brownian diffusion and electrostatic forces (Brochot et al, 2019;Lindsley, 2016;Zíková et al, 2015). The resulting component of these forces is translated into a function that displays near 100 % collection efficiency for particles smaller than 20 nm and larger than 300 nm.…”

A model framework to retrieve thermodynamic and kinetic properties of organic aerosol from composition-resolved thermal desorption measurements

“…b Assumptions of particle phase state are invalid. For instance, the organic constituents may not be ideally mixed (Robinson et al, 2015;Zuend and Seinfeld, 2012). Also, several types of ambient biogenic SOA particles have been shown to be not liquid, at least at certain humidity ranges, but to rather adopt an amorphous semisolid (i.e., glassy) state (Virtanen et al, 2010;Pajunoja et al, 2016).…”

Chemical discrimination of the particulate and gas phases of miniCAST exhausts using a two-filter collection method

“…The desorbed plume propagates normally from the sample surface in between the extraction plates of the ToF-MS. The molecules from the desorbed plume are then ionized by either a resonant two-photon ionization R2PI (Haefliger and Zenobi, 1998;Mihesan et al, 2006;Zimmermann et al, 2001) process at λ i = 266 nm (4 ns width pulsed UV laser, Continuum Powerlite, 1 mJ pulse −1 ) or a single-photon ionization (SPI) process at λ i = 157 nm (5 ns width pulsed vacuum ultraviolet (VUV) excimer laser, Coherent ExciStar XS 200) or λ i = 118 nm (in-house built coherent nanosecond source). The ninth harmonic of the Nd:YAG laser (λ i = 118.2 nm) was generated by tripling the 355 nm output of a Continuum Surelite pulsed laser in a Xe cell (Hilbig, 1982;Popovicheva et al, 2017).…”