In situ product monitoring in heterogeneous reaction of gaseous trimethylamine on Fe₂O₃/Fe(NO₃)₃: Effect of environmental factor and particle property.

Authors

Chenxu Gao, Cheng Chen, Jiangyao Chen

Published in

Journal of environmental sciences (China). Volume 168. Pages 530-537. Epub Jan 07, 2026.

Abstract

Gas-particle reactions represent an important atmospheric heterogeneous transformation process for organic amines (OAs). Environmental factors and particle properties may impact the gas-particle reaction products. Although the products from gas-particle reactions can be monitored by various in situ techniques, related data remain scarce. Here, the interfacial and gaseous products from the reaction of trimethylamine on Fe₂O₃/Fe(NO₃)₃ particles under light irradiation with mixed NO₂, O₂, SO₂ and H₂O were monitored using in-situ diffuse reflectance Fourier transform infrared spectroscopy and proton transfer reaction time-of-flight mass spectrometry. Dark reaction of gaseous trimethylamine on Fe₂O₃/Fe(NO₃)₃ generated two interfacial products types: N-containing ones (CH₃NCH₂, CH₃NO₂, (CH₃)₂NCHO, and CH₃N(OH)CHO) and N-free ones (alcohols, aldehydes and acids), both accumulating with reaction progression. Light irradiation and O₂ oxidation enhanced formation of these products, while NO₂ promoted the production of CH₃NO₂ and (CH₃)₂NCHO. H₂O and SO₂ occupied the active sites of particles to inhibit the formation of all products. Compared to Fe(NO₃)₃, Fe₂O₃ showed absolute dominance in contribution to the formation of products. Considering the smaller particle size of Fe₂O₃ and excess Fe(NO₃)₃, the physical mixing of them reduced the generation of interfacial products. Furthermore, gaseous products of CH₃OH, HCHO, CH₃CHO, HCOOH and CH₃COOH detection clarified the N-free interfacial products. The presence of Fe(NO₃)₃ inhibited the formation of HCOOH and favored the formation of CH₃CHO in the gas phase. By combining product information with thermodynamic calculations, the heterogeneous reaction pathways of trimethylamine were tentatively proposed. These findings provide a guiding significance for the migration of OAs in real atmospheric environment.

PMID:
42680411
Bibliographic data and abstract were imported from PubMed on 02 Sep 2026.

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