Quantifying the entrainment of carbon black nanoparticles from surfaces by impinging air jets

摘要

The removal and inhalation of particles from nanoparticle coatings is a growing concern in the environment. In order to better understand the effects of these released nanoparticles on human health, the particles must be quantified in both their size and concentration distributions. To simulate conditions in the environment, a fine layer of carbon black aerosol nanoparticles was deposited onto a glass substrate through diffusional deposition of a low flow of air containing carbon black particles. The resulting aggregates ranged from approximately 40 nanometers to 20 micrometers. The substrate was passed through a series of air jets, and the amount of remaining carbon along the center of the surface was measured each time. By finding the surface area coverage at a location on the slide measured by scanning electron microscopy and assigning it to the intensity fraction at the same location measured by the optical setup, the optical readings were calibrated. The calibration data was used to interpolate the surface coverage based on further optical measurements. Preliminary experiments have indicated a removal of about 0.5 percent surface coverage. As experiments continue, the procedures for each setup are further refined to allow for greater sensitivity in capturing the removal of carbon black particles from the surface. In addition, these data will be used for modeling the size and concentration distributions of particles given re-entrainment parameters.