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Effect of Relative Humidity on Aerosol Generation through Experiments at Low Concentrations of Gaseous Nitric Acid and Ammonia

Category: Articles

Volume: 7 | Issue: 2 | Pages: 193-204
DOI: 10.4209/aaqr.2006.10.0023

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Hitomi Kobara 1, Koji Takeuchi1, Takashi Ibusuki2

  • 1 National Institute of Advanced Industrial Science and Technology, AIST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
  • 2 Japan Environmental Management Association for Industry, (null), Japan


Particle generation of ammonium nitrate from gaseous nitric acid and ammonia at low concentrations (100-600 ppbv) was investigated using a flow-type reactor with a silanized inner wall for deactivation. The particle number concentration of the generated aerosols was maximum at a constant relative humidity (RH) of around 60% in experiments at different gas concentrations. The RH of 60% coincides with the deliquescence relative humidity (DRH) of ammonium nitrate, and the physical state of particles is thought to be different below and above DRH. The size distribution of the particles was greatly affected by the RH. The NH4NO3 content in the wet particles was measured and compared with the value derived from the hydration-dehydration cycle. This report provides a simple and convenient method to generate NH4NO3 particles.


Deliquescence relative humidity Ammonium nitrate Particle generation

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