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New Insights into the Degradation of Atrazine by Ultraviolet-Based Techniques
https://orcid.org/0000-0001-9176-5049
https://orcid.org/0000-0002-3585-6541
https://orcid.org/0000-0002-0802-1629
The combination of ultraviolet (UV) light and H2O2 is generally considered a promising technology for removing atrazine from the aqueous environment due to its high degradation efficiency, but the generation of toxic chloro-dealkylated intermediates is usually neglected. In addition, the dechlorination mechanism of the UV/H2O2 system has seldom been investigated. In this study, atrazine degradation is comparatively investigated in the UV and UV/H2O2 systems to clarify the dechlorination mechanism. The results show that direct UV photolysis can induce dechlorination of atrazine to form nontoxic hydroxyatrazine via a nucleophilic substitution reaction of 3atrazine* with nucleophile H2O. For comparison, the degradation rate of atrazine can be enhanced in the UV/H2O2 system but the dechlorination efficiency is dramatically inhibited because in situ-generated •OH preferentially attacks the side chains of atrazine to form chloro-dealkylated intermediates. Meanwhile, further dechlorination of chloro-dealkylated intermediates by H2O via nucleophilic substitution under UV irradiation is substantially slower than that of atrazine. In addition, laser flash photolysis combined with theoretical calculation also confirms that 3chloro-dealkylation intermediates* are more resistant to dechlorination than 3atrazine*. Overall, this study suggests that it is not beneficial to upgrade direct UV photolysis to the UV/H2O2 system for degrading atrazine in light of the dechlorination efficiency.
This study sheds light on the mechanism of dechlorination during atrazine degradation in the ultraviolet (UV) and UV/H2O2 systems.
New Insights into the Degradation of Atrazine by Ultraviolet-Based Techniques
https://orcid.org/0000-0001-9176-5049
https://orcid.org/0000-0002-3585-6541
https://orcid.org/0000-0002-0802-1629
The combination of ultraviolet (UV) light and H2O2 is generally considered a promising technology for removing atrazine from the aqueous environment due to its high degradation efficiency, but the generation of toxic chloro-dealkylated intermediates is usually neglected. In addition, the dechlorination mechanism of the UV/H2O2 system has seldom been investigated. In this study, atrazine degradation is comparatively investigated in the UV and UV/H2O2 systems to clarify the dechlorination mechanism. The results show that direct UV photolysis can induce dechlorination of atrazine to form nontoxic hydroxyatrazine via a nucleophilic substitution reaction of 3atrazine* with nucleophile H2O. For comparison, the degradation rate of atrazine can be enhanced in the UV/H2O2 system but the dechlorination efficiency is dramatically inhibited because in situ-generated •OH preferentially attacks the side chains of atrazine to form chloro-dealkylated intermediates. Meanwhile, further dechlorination of chloro-dealkylated intermediates by H2O via nucleophilic substitution under UV irradiation is substantially slower than that of atrazine. In addition, laser flash photolysis combined with theoretical calculation also confirms that 3chloro-dealkylation intermediates* are more resistant to dechlorination than 3atrazine*. Overall, this study suggests that it is not beneficial to upgrade direct UV photolysis to the UV/H2O2 system for degrading atrazine in light of the dechlorination efficiency.
This study sheds light on the mechanism of dechlorination during atrazine degradation in the ultraviolet (UV) and UV/H2O2 systems.
New Insights into the Degradation of Atrazine by Ultraviolet-Based Techniques
https://orcid.org/0000-0001-9176-5049
https://orcid.org/0000-0002-3585-6541
https://orcid.org/0000-0002-0802-1629
The combination of ultraviolet (UV) light and H2O2 is generally considered a promising technology for removing atrazine from the aqueous environment due to its high degradation efficiency, but the generation of toxic chloro-dealkylated intermediates is usually neglected. In addition, the dechlorination mechanism of the UV/H2O2 system has seldom been investigated. In this study, atrazine degradation is comparatively investigated in the UV and UV/H2O2 systems to clarify the dechlorination mechanism. The results show that direct UV photolysis can induce dechlorination of atrazine to form nontoxic hydroxyatrazine via a nucleophilic substitution reaction of 3atrazine* with nucleophile H2O. For comparison, the degradation rate of atrazine can be enhanced in the UV/H2O2 system but the dechlorination efficiency is dramatically inhibited because in situ-generated •OH preferentially attacks the side chains of atrazine to form chloro-dealkylated intermediates. Meanwhile, further dechlorination of chloro-dealkylated intermediates by H2O via nucleophilic substitution under UV irradiation is substantially slower than that of atrazine. In addition, laser flash photolysis combined with theoretical calculation also confirms that 3chloro-dealkylation intermediates* are more resistant to dechlorination than 3atrazine*. Overall, this study suggests that it is not beneficial to upgrade direct UV photolysis to the UV/H2O2 system for degrading atrazine in light of the dechlorination efficiency.
This study sheds light on the mechanism of dechlorination during atrazine degradation in the ultraviolet (UV) and UV/H2O2 systems.
New Insights into the Degradation of Atrazine by Ultraviolet-Based Techniques
Mu, Yi (author) / Chen, Ying (author) / Chen, Peng (author) / Qin, Lumei (author) / Zou, Jian-Ping (author) / Wu, Meifeng (author) / Luo, Sheng-lian (author)
ACS ES&T Water ; 1 ; 958-968
2021-04-09
Article (Journal)
Electronic Resource
English
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