Iodine-sensitized degradation of 2,4,6-trichlorophenol under visible light

Hu, Meiqin, Wang, Yan, Xiong, Zhigang, Bi, Dongqin, Zhang, Yuhong and Xu, Yiming (2012) Iodine-sensitized degradation of 2,4,6-trichlorophenol under visible light. Environmental Science and Technology, 46 16: 9005-9011. doi:10.1021/es301577p

Author Hu, Meiqin
Wang, Yan
Xiong, Zhigang
Bi, Dongqin
Zhang, Yuhong
Xu, Yiming
Title Iodine-sensitized degradation of 2,4,6-trichlorophenol under visible light
Journal name Environmental Science and Technology   Check publisher's open access policy
ISSN 0013-936X
Publication date 2012-08-21
Sub-type Article (original research)
DOI 10.1021/es301577p
Volume 46
Issue 16
Start page 9005
End page 9011
Total pages 7
Place of publication Washington, DC, United States
Publisher American Chemical Society
Collection year 2013
Language eng
Formatted abstract
Molecular iodine has been studied, for the first time, as a sensitizer for the degradation of 2,4,6-trichlorophenol (TCP) in aqueous solution under visible light (λ ≥ 450 nm). TCP was degraded in the presence of commercial I2, but the reaction rate decreased significantly after 2 h. When a solution of NaI and H2O2 was used as an iodine source with phosphotungstic acid (PW) as a catalyst, TCP degradation was not only fast but also followed zero-order kinetics. Importantly, the I2 concentration remained unchanged with time, indicative of I2 recycling as a kind of photocatalyst. During TCP degradation, 2,6-dichloro-1,4-benzoquinone was produced as the main intermediate (76%), which slowly degraded in the irradiated solution. For every equivalent of TCP consumed at the 2 h time point, approximately 1.7 equivalents of chloride ions were produced. Further study of the effect of variables including the type of polyoxometalates (POM) and the initial concentration of each component revealed that the rate of TCP degradation under visible light was determined by the rate of I2 production in the dark. The optimum pH and apparent activation energy for TCP disappearance were 4.5 and 42.8 kJ/mol, respectively. It is proposed that TCP degradation is initiated by iodine radicals produced from I2 photolysis, followed by I2 regeneration through a POM-catalyzed oxidation of I3 by H2O2.
Keyword Hydrogen peroxide
Aqueous solution
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
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Created: Fri, 05 Oct 2012, 19:27:43 EST by System User on behalf of School of Chemical Engineering