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Unveiling the Photodegradation Mechanism of Monochlorinated Naphthalenes under UV-C Irradiation: Affecting Factors Analysis, the Roles of Hydroxyl Radicals, and DFT Calculation

Authors :
Yingtan Yu
Mengdi Liu
Shimeng Wang
Chaoxing Zhang
Xue Zhang
Li Liu
Shuang Xue
Source :
Molecules, Vol 29, Iss 19, p 4535 (2024)
Publication Year :
2024
Publisher :
MDPI AG, 2024.

Abstract

Polychlorinated naphthalenes (PCNs) are a new type of persistent organic pollutant (POP) characterized by persistence, bioaccumulation, dioxin-like toxicity, and long-range atmospheric transport. Focusing on one type of PCN, monochlorinated naphthalenes (CN-1, CN-2), this study aimed to examine their photodegradation in the environment. In this work, CN-1 and CN-2 were employed as the model pollutants to investigate their photodegradation process under UV-C irradiation. Factors like the pH, initial concentrations of CN-1, and inorganic anions were investigated. Next, the roles of hydroxyl radicals (•OH), superoxide anion radicals (O2•−), and singlet oxygen (1O2) in the photodegradation process were discussed and proposed via theory computation. The results show that the photodegradation of CN-1 and CN-2 follows pseudo-first-order kinetics. Acidic conditions promote the photodegradation of CN-1, while the effects of pH on the photodegradation of CN-2 are not remarkable. Cl−, NO3−, and SO32− accelerate the photodegradation of CN-1, whereas the effect of SO42− and CO32− is not significant. Additionally, the contributions of •OH and O2•− to the photodegradation of CN-1 are 20.47% and 38.80%, while, for CN-2, the contribution is 16.40% and 16.80%, respectively. Moreover, the contribution of 1O2 is 15.7%. Based on DFT calculations, C4 and C6 of the CN-1 benzene ring are prioritized attack sites for •OH, while C2 and C9 of CN-2 are prioritized attack sites.

Details

Language :
English
ISSN :
14203049
Volume :
29
Issue :
19
Database :
Directory of Open Access Journals
Journal :
Molecules
Publication Type :
Academic Journal
Accession number :
edsdoj.4d77dc9f70d3440db873a4f739772b94
Document Type :
article
Full Text :
https://doi.org/10.3390/molecules29194535