Reactivity of aminophenols in forming nitrogen-containing brown carbon from iron-catalyzed reactions

Authors

Hind A. Al-Abadleh, Wilfrid Laurier UniversityFollow
Fatemeh Motaghedi, Wilfrid Laurier University
Wisam Mohammed, Wilfrid Laurier University
Md. Sohel Rana, University of KentuckyFollow
Kotiba A. Malek, University of Maryland at College Park
Dewansh Rastogi, University of Maryland at College Park
Akua A. Asa-Awuku, University of Maryland at College ParkFollow
Marcelo I. Guzman, University of KentuckyFollow

Abstract

Nitrogen-containing organic carbon (NOC) in atmospheric particles is an important class of brown carbon (BrC). Redox active NOC like aminophenols received little attention in their ability to form BrC. Here we show that iron can catalyze dark oxidative oligomerization of o- and p-aminophenols under simulated aerosol and cloud conditions (pH 1–7, and ionic strength 0.01–1 M). Homogeneous aqueous phase reactions were conducted using soluble Fe(III), where particle growth/agglomeration were monitored using dynamic light scattering. Mass yield experiments of insoluble soot-like dark brown to black particles were as high as 40%. Hygroscopicity growth factors (κ) of these insoluble products under sub- and super-saturated conditions ranged from 0.4–0.6, higher than that of levoglucosan, a prominent proxy for biomass burning organic aerosol (BBOA). Soluble products analyzed using chromatography and mass spectrometry revealed the formation of ring coupling products of o- and p-aminophenols and their primary oxidation products. Heterogeneous reactions of aminophenol were also conducted using Arizona Test Dust (AZTD) under simulated aging conditions, and showed clear changes to optical properties, morphology, mixing state, and chemical composition. These results highlight the important role of iron redox chemistry in BrC formation under atmospherically relevant conditions.

Document Type

Article

Publication Date

9-19-2022

Notes/Citation Information

Published in Communications Chemistry , 2022, v. 5, Article number: 112

Digital Object Identifier (DOI)

10.1038/s42004-022-00732-1

Funding Information

U.S.A. National Science Foundation under award 1903744 to M.I.G.

Repository Citation

Al-Abadleh, Hind A.; Motaghedi, Fatemeh; Mohammed, Wisam; Rana, Md. Sohel; Malek, Kotiba A.; Rastogi, Dewansh; Asa-Awuku, Akua A.; and Guzman, Marcelo I., "Reactivity of aminophenols in forming nitrogen-containing brown carbon from iron-catalyzed reactions" (2022). Chemistry Faculty Publications. 195.
https://uknowledge.uky.edu/chemistry_facpub/195