Laboratory and modelling study of the hygroscopic properties of two model humic acid aerosol particles

FD Pope, L Harper, BJ Dennis-Smither, PT Griffiths, SL Clegg, RA Cox

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11 Citations (Scopus)

Abstract

The hygroscopic properties of aerosol particles, composed of two different commercially available humic acids, have been investigated in the temperature range 293-295. K as a function of relative humidity using an electrodynamic balance. The measured mass growth factors of Sigma-Aldrich humic acid sodium salt (NaHA) and leonardite humic acid (LHA) at 90% relative humidity are 1.87±0.02 and 1.20±0.05, respectively. There is a general agreement between the results described in this study with previous TDMA results, which are undertaken with smaller particle ensembles and shorter aerosol-water equilibration times. The measured mass growth factors of Sigma-Aldrich humic acid sodium salt (NaHA) and leonardite humic acid (LHA) at 90% relative humidity are 1.87±0.05 and 1.20±0.05, respectively. The UNIFAC model was used to calculate the relationship between water activity and the concentrations of a modelled LHA molecule, and thus the hygroscopicity. The LHA molecule was modelled by both the Steelink monomer and the Northeastern-Temple-Birmingham humic acid monomer structural models.
Original languageEnglish
Pages (from-to)457-467
Number of pages11
JournalJournal of Aerosol Science
Volume41
Issue number5
DOIs
Publication statusPublished - 2010

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