Impact of the versatile aerosol concentration enrichment system (VACES) on gas phase species

Heejung Jung, Chuautemoc Arellanes, Yongjing Zhao, Suzanne Paulson, Cort Anastasio, Anthony Wexler

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The performance of the Versatile Aerosol Concentration Enrichment System (VACES) was assessed in terms of the enrichment factor (EF) for highly soluble vapors. Gases ranged in their behavior from a slight enrichment for ammonia (EF(NH3) = 1.9 ± 0.8) to strong depletion of nitric acid (EF(HNO3) = 0.12 ± 0.06). H2O2 fell in between, with EF(H2O2) averaging 0.37 (± 0.25) and ranging from 0.07 and 0.91 depending on conditions. Detailed results for H 2O2 indicate that there are two competing processes at play: soluble gases are lost to condensed water in the VACES, particularly in the saturator water bath but also other locations, depleting outlet gas-phase concentrations and resulting in EFs well below 1. Working in the opposite direction, H2O2 (and other soluble gases) can also be concentrated together with particles. Presumably, the gases are absorbed into the particles as they take up water, pass through the concentration step, and are released once particles are re-dried. Depending on conditions and the gas solubility, depletion and concentration play larger or smaller roles. The relative importance of these competing processes appear to follow in order of Henry's law solubilities, with modest particle-mediated concentration (resulting in EFs > 1) dominating for ammonia, the least soluble gas, and loss in the water bath and other condensed water in the VACES dominating for H 2O2 and HNO3, which are more soluble (i.e., have higher Henry's law coefficients).

Original languageEnglish (US)
Pages (from-to)1113-1121
Number of pages9
JournalAerosol Science and Technology
Issue number12
StatePublished - Dec 2010

ASJC Scopus subject areas

  • Materials Science(all)
  • Environmental Chemistry
  • Pollution


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