TY - JOUR
T1 - Hygroscopicity and Compositional Evolution of Atmospheric Aerosols Containing Water-Soluble Carboxylic Acid Salts and Ammonium Sulfate
T2 - Influence of Ammonium Depletion
AU - Wang, Na
AU - Jing, Bo
AU - Wang, Pan
AU - Wang, Zhen
AU - Li, Jiarong
AU - Pang, Shufeng
AU - Zhang, Yunhong
AU - Ge, Maofa
N1 - Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019/6/4
Y1 - 2019/6/4
N2 - Water-soluble organic acid salts are important components of atmospheric aerosols. Despite their importance, it is still not clear how water-soluble organic acid salts influence interactions between aerosols and water vapor in the atmosphere. In this study, the hygroscopic behaviors and chemical compositions of aerosol particles containing water-soluble organic acid salt ((CH2)n(COONa)2, n = 0, 1, 2) and (NH4)2SO4 were measured using in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The ammonium depletion due to release of gaseous NH3 was found in mixed aerosols composed of (CH2)n(COONa)2 (n = 1, 2) and (NH4)2SO4 upon dehydration. The ammonium loss could modify the aerosol composition, resulting in the formation of corresponding organic acid and monosodium dicarboxylate in mixed particles with high and low (NH4)2SO4 content, respectively. Due to the weaker hydrolysis of oxalate anions, the ammonium depletion was not observed for the Na2C2O4/(NH4)2SO4 mixtures. The changes in the particle composition led to the decreased water uptake upon hydration as compared to that upon dehydration. Our findings reveal that interactions between water-soluble organic acid salts and (NH4)2SO4 in aqueous aerosols may affect the repartition of NH3 between the condensed and gas phases, thus modifying composition and physicochemical properties of aerosols as well as relevant chemical processes.
AB - Water-soluble organic acid salts are important components of atmospheric aerosols. Despite their importance, it is still not clear how water-soluble organic acid salts influence interactions between aerosols and water vapor in the atmosphere. In this study, the hygroscopic behaviors and chemical compositions of aerosol particles containing water-soluble organic acid salt ((CH2)n(COONa)2, n = 0, 1, 2) and (NH4)2SO4 were measured using in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The ammonium depletion due to release of gaseous NH3 was found in mixed aerosols composed of (CH2)n(COONa)2 (n = 1, 2) and (NH4)2SO4 upon dehydration. The ammonium loss could modify the aerosol composition, resulting in the formation of corresponding organic acid and monosodium dicarboxylate in mixed particles with high and low (NH4)2SO4 content, respectively. Due to the weaker hydrolysis of oxalate anions, the ammonium depletion was not observed for the Na2C2O4/(NH4)2SO4 mixtures. The changes in the particle composition led to the decreased water uptake upon hydration as compared to that upon dehydration. Our findings reveal that interactions between water-soluble organic acid salts and (NH4)2SO4 in aqueous aerosols may affect the repartition of NH3 between the condensed and gas phases, thus modifying composition and physicochemical properties of aerosols as well as relevant chemical processes.
UR - http://www.scopus.com/inward/record.url?scp=85064827171&partnerID=8YFLogxK
U2 - 10.1021/acs.est.8b07052
DO - 10.1021/acs.est.8b07052
M3 - Article
C2 - 30938517
AN - SCOPUS:85064827171
SN - 0013-936X
VL - 53
SP - 6225
EP - 6234
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 11
ER -