Issue 3, 2021

Degradation mechanisms of simple aliphatic amines under ozonation: a DFT study

Abstract

Aliphatic amines as common constituents of dissolved organic nitrogen (DON) exhibit high reactivity during ozonation; however, our understanding of their degradation mechanisms is very limited. In this study, methylamine (MA) and ethylamine (EA), as well as their secondary and tertiary amines (DMA, DEA, TMA and TEA) were chosen as aliphatic amine models and their degradation mechanisms during ozonation were investigated by using the DFT method. The oxygen-transfer reaction occurs initially and rapidly in the ozonation of all the above amines with a ΔG value of 8–10 kcal mol−1 in great agreement with the experimental rate constant of 104 to 107 M−1 s−1. Moreover, N-oxide as the main degradation product for tertiary amines directly forms after oxygen-transfer, while nitroalkanes as main products for secondary and primary amines are yielded after a series of reactions mediated by hydroxylamine and nitrosoalkane with a ΔG value of 10–13 kcal mol−1. Regarding the minor N-dealkylated products for all amines, alkylamino alcohol is an important intermediate possibly generated via a radical reaction pathway with a ΔG value of 21–34 kcal mol−1. Additionally, comparison of the reactivity of aliphatic amines, hydroxylamines and alkylamino alcohols with ozone was made and elucidated in this study. The results are expected to expand our understanding of the degradation mechanisms for nitrogenous compounds during ozonation.

Graphical abstract: Degradation mechanisms of simple aliphatic amines under ozonation: a DFT study

Supplementary files

Article information

Article type
Paper
Submitted
18 11月 2020
Accepted
22 1月 2021
First published
24 1月 2021

Environ. Sci.: Processes Impacts, 2021,23, 480-490

Degradation mechanisms of simple aliphatic amines under ozonation: a DFT study

Q. Shen, Y. D. Liu and R. Zhong, Environ. Sci.: Processes Impacts, 2021, 23, 480 DOI: 10.1039/D0EM00476F

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements