The High Charge Fraction of Flame-Generated Particles in the Size Range below 3 nm Measured by Enhanced Particle Detectors
Charging in flames significantly affects the properties of the resultant particles produced because of its influence in almost all stages of particle formation. The charging characteristics of flame-generated sub-3 nm particles were investigated with three enhanced particle detectors including a high resolution differential mobility analyzer (DMA) coupled with an electrometer, a particle size magnifier coupled with a butanol-based condensation particle counter (PSM-bCPC), and an atmospheric pressure interface time-of-flight mass spectrometer (APi-TOF). Up to 95% of the flame-generated sub-3 nm particles were charged at a sampling height of 5 mm above the burner, indicating the existence of a strong ionization process in the investigated flame. This high fraction of charged particles contradicts the classical charging theories, which predict < 1% charge fraction for particles below 3 nm. Positively and negatively charged sub-3 nm particles generated from a blank flame were dominated by organic ions and nitrate ions respectively. The flame-generated ions play an important role during titanium dioxide (TiO2) nanoparticle synthesis, as shown by the attachment of nitrate species on Ti-containing particles observed by the APi-TOF. The effects of the sampling height and precursor feed rate were also investigated.
Y. Wang et al., "The High Charge Fraction of Flame-Generated Particles in the Size Range below 3 nm Measured by Enhanced Particle Detectors," Combustion and Flame, vol. 176, pp. 72-80, Elsevier, Feb 2017.
The definitive version is available at https://doi.org/10.1016/j.combustflame.2016.10.003
Civil, Architectural and Environmental Engineering
Keywords and Phrases
Atmospheric pressure; Electric charge; Ions; Mass spectrometers; Mass spectrometry; Nitrates; Oxides; Particle detectors; Particle size; Synthesis (chemical); Titanium dioxide; Charge fractions; Charging characteristics; Condensation particle counters; Differential mobility analyzers; Nanoparticle synthesis; Particle formations; Time-of-flight mass spectrometers; Titanium dioxides (TiO2); Flame synthesis; Anion; Butanol; Nitrate; Titanium dioxide nanoparticle; Article; Atmospheric pressure; Controlled study; Flame; Fractionation; Ionization; Particle size; Polymerization; Priority journal; Synthesis; Time of flight mass spectrometry; Sub-3 nm particle
International Standard Serial Number (ISSN)
Article - Journal
© 2017 The Combustion Institute, All rights reserved.
01 Feb 2017