Synthesis of an Ultrafine Iron and Soot Aerosol for the Evaluation of Particle Toxicity

Abstract

A diffusion ame system was used to generate an aerosol of soot and iron oxide. The primary fuel was ethylene. Iron was introduced by passing ethylene over liquid iron pentacarbonyl. The aerosol emission from the ame was diluted by secondary air to a level that could be used in animal exposure studies. The system was designed to operate at a constant soot production rate while the iron loading was varied from 0 to 50 ¹g m 3 in the diluted post ame gases. The impact of the iron on soot production was counteracted by the addition of acetylene to the fuel. Particles were collected on carbon grids and were examined via transmission electron microscopy. Electron energy loss spectroscopy was employed to characterize the aerosol. A differential mobility analyzer was used to measure the size distribution of the aerosol. The iron particles were typically 40 nm in diameter and often appeared in isolation from the soot aerosol, suggesting that either they were not formed concurrently with the soot or they remained after oxidation of the surrounding soot. Samples collected from within the ame, and downstream of the ame, indicated that the iron may have been present as very small particles comingled with the soot. The iron particles apparently melted and coalesced as they passed through the high temperature ame tip. Crystallization of the iron proceeded as the post ame gases cooled by mixing with external air. The ame system was shown to be capable of consistently producing steady concentrations of soot and iron for delivery to animals, without the confounding presence of toxic gaseous compounds.

High spatial resolution laser cavity extinction and laser-induced incandescence in low-soot-producing flames

“…* B. Tian bt312@cam.ac.uk 1 Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK P 0 Single-pass laser extinction projection P t Total laser extinction projection R Product of the reflectivity of the two cavity mirrors r Radial coordinate r 0 Inner radius of fuel tube r 1 Reflectance of mirror 1 r 2 Reflectance of mirror 2 S D LII signal intensity for single soot particle S LII Integrated LII signal intensity with probe volume T Product of the transmittance of the two cavity mirrors t 1 Transmittance of mirror 1 t 2 Transmittance of mirror 2 T p…”

“…Soot particles generated from combustion are both a significant atmospheric pollutant and a contributor to climate change [1][2][3][4]. Many techniques have therefore been developed to measure soot particles from a variety of sources, both via sampling and via non-intrusive techniques.…”

Gas-Phase Flame Synthesis and Characterization of Iron Oxide Nanoparticles for Use in a Health Effects Study

“…A H 2 flame was used to prevent carbon contamination of the nanoparticles that is likely with a hydrocarbon flame (Zhou et al 2003a). Although the formation of iron oxide nanoparticles in flames has been previously investigated in a number of studies (Janzen et al 2002;Jossen et al 2005;McMillin et al 1996;Rumminger and Linteris 2000;Yang et al 2001), this article reports a significant feature of the iron oxide nanoparticles synthesized in this study: ultrafine nanoparticles of iron oxide (3-8 nm in diameter). Such small iron oxide particles have been briefly discussed in the recently published health effects study (Gojova et al 2007), but no detailed characterization and discussion of the small particles' origin were given in that work.…”

“…Previous toxicity studies (Zhou et al 2003a(Zhou et al , 2003b have used flame synthesized iron-bearing particles. The synthesis and characterization of these particles were well-characterized (Yang et al 2001); such documentation is obviously necessary for finding the correlation between toxicity and particle properties.…”

Aerosolization System for Experimental Inhalation Studies of Carbon-Based Nanomaterials

“…For example, a system encompassing an acoustic fluidization feeder, mill, and size separator was used to generate aerosolized single-walled carbon nanotubes (SW-CNTs; Baron et al 2008), whereas a jet mill coupled to a dry chemical screw feeder (Mitchell et al 2007) or a 6-jet collision nebulizer (Ryman-Rasmussen et al 2008) was utilized to aerosolize multiwalled carbon nanotubes (MW-CNTs). Other test systems employed for generating nanomaterials have included a brush dust generator for inhalation studies of nanotitanium dioxide (Ma-Hock et al 2009), as well as a direct delivery of aerosolized nanomaterials from an evaporation reactor (e.g., silicon dioxide; Ostraat et al 2008) or combustion with a laminar diffusion flame system (e.g., ultrafine iron; Yang et al 2001). Researchers have also compared the consistency, homogeneity, and size distribution of aerosols of nanomaterials generated by a variety of wet and dry aerosolization systems (Schmoll et al 2009).…”