AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Size-Resolved Acid:Base Ratio of Atomized Nanoparticles from Salt Solutions
SABRINA CHEE, Haihan Chen, Michael J. Lawler, James Smith, University of California, Irvine
Abstract Number: 648 Working Group: Instrumentation and Methods
Abstract Bulk solutions comprised of sulfuric acid and ammonia or amines are commonly aerosolized at varying pH as a source of seed particles in studies of secondary organic aerosol formation and cloud droplet activation. However, during atomization, relatively volatile ammonia and amines may evaporate from the droplets before the formation of low-volatility acid-base pairs. This may result in particles that are more acidic than the bulk solution. This phenomenon may happen to differing degrees depending on particle size as well as the concentration and ratio of acid and base in solution. To test this, we atomized aqueous solutions containing sulfuric acid and ammonia or amine, size selected nanoparticles with a nano differential mobility analyser (nanoDMA), and collected particles for analysis on aluminium and quartz filter substrates with a sequential spot sampler (Aerosol Devices, Inc.). We quantified the acid:base ratio of size-resolved nanoparticles by extracting the sample into solvent and analysing the solution with Ion Chromatography (IC) coupled with a conductivity detector. Results of this study are discussed, as well as its implications for the use of atomizers for generating nanoparticles consisting of these compounds