Toward a better understanding of ferric-oxalate complex photolysis: The role of the aqueous/air interface of droplet

Yu Wang; Marcello Brigante; Gilles Mailhot; David Talaga; Yanlin Wu; Wenbo Dong; Sophie Sobanska

doi:10.1016/j.chemosphere.2021.133127

Toward a better understanding of ferric-oxalate complex photolysis: The role of the aqueous/air interface of droplet

Chemosphere. 2022 Feb:289:133127. doi: 10.1016/j.chemosphere.2021.133127. Epub 2021 Dec 2.

Authors

Yu Wang¹, Marcello Brigante², Gilles Mailhot², David Talaga³, Yanlin Wu⁴, Wenbo Dong⁵, Sophie Sobanska⁶

Affiliations

¹ Department of Environmental Science & Engineering, Fudan University, Shanghai, 200438, China; Institut des Sciences Moléculaires, UMR CNRS 5255, Univ. Bordeaux, Talence, F-33405, France.
² Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut de Chimie de Clermont-Ferrand, F-63000, Clermont-Ferrand, France.
³ Institut des Sciences Moléculaires, UMR CNRS 5255, Univ. Bordeaux, Talence, F-33405, France.
⁴ Department of Environmental Science & Engineering, Fudan University, Shanghai, 200438, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
⁵ Department of Environmental Science & Engineering, Fudan University, Shanghai, 200438, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China. Electronic address: wbdong@fudan.edu.cn.
⁶ Institut des Sciences Moléculaires, UMR CNRS 5255, Univ. Bordeaux, Talence, F-33405, France. Electronic address: sophie.sobanska@u-bordeaux.fr.

PMID: 34864008
DOI: 10.1016/j.chemosphere.2021.133127

Abstract

In this work, the photo reactivity of ferric oxalate (Fe(III)-Ox) complex in atmospheric particles was investigated. Raman spectroscopy was used to explore the mechanism and kinetics of Fe(III)-Ox photolysis occurring at the aqueous/gas interface, inside the droplet and in bulk solution. Ferrous carbonate (FeCO₃) was detected indicating that carbonate ion (CO₃^2-) formed inside the droplets would compete with oxalate ligands for iron complexation. A higher concentration of photoproduct Fe(II)-Ox was observed at the surface and inside of the droplets than in bulk solution. In particular, Fe(III)-Ox on the droplet surface was quickly reduced with light and Fe(II)-Ox concentration gradually decreased with irradiation time. The evolution of Fe(II)-Ox concentration was similar inside the droplet and in bulk solution with a trend of first increasing and then gradually decreasing during irradiation time. Although FeCO₃ would hinder Fenton intermediate reaction, the photolysis rate of Fe(III)-Ox in droplets was almost two orders of magnitude times faster than that observed during bulk experiment. In general, the photolysis mechanism and kinetics of Fe(III)-Ox in aqueous/air interface, inside of droplet and bulk solution were distinct, and the production of oxide species from the atmospheric Fe(III)-Ox droplets was underestimated.

Keywords: Atmospheric chemistry; Ferric oxalate; Photolysis; Raman spectroscopy; Surface chemistry.

MeSH terms

Ferric Compounds*
Ferrous Compounds
Iron
Oxalic Acid*
Photolysis

Substances

Ferric Compounds
Ferrous Compounds
Oxalic Acid
Iron