Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/34655
Title: Reaction mechanism of photoreduction of 2, 4-dichlorophenoxyacetic acid in surfactant micelles
Authors: Kwan, CY
Chu, W 
Issue Date: 2005
Publisher: ACS Publications
Source: Industrial & engineering chemistry research, 2005, v. 44, no. 6, p. 1645-1651 How to cite?
Journal: Industrial & engineering chemistry research
Abstract: The direct photolysis of 2,4-dichlorophenoxyacetic acid (2,4-D) in water is slow and ineffective, but surfactant micelles can greatly enhance the photochemical reaction of organic contaminants. The effect of an anionic (sodium dodecyl sulfate), a cationic (cetyltrimethylammonium bromide), and two nonionic (Brij 35, Tween 80) surfactants on the phototransformation of 2,4-D at 253.7 nm was examined. Except for the anionic surfactant, the other micelles were significant facilitators in both removal efficiencies and decay rates of 2,4-D. This herbicide was then irradiated in the presence of Brij 35 micelles at five different initial pH levels. 2,4-D is an organic acid, and its speciation (molecular or ionic form) is controlled by pH. It was found that the photoreduction of 2,4-D was more effective at lower initial pH than that in basic conditions. The transformation of 2,4-D in micelles occurred predominantly through reductive chlorination, resulting in generation of less chlorinated products. The presence of hydroxylated products in low yields indicated photohydrolysis was a minor competitive reaction pathway. The measurable intermediates were 2-chlorophenoxyacetic acid, 4-chlorophenoxyacetic, chlorohydroxyphenoxyacetic acid, phenoxyacetic acid, hydroxyphenyoxyacetic acid, and phenol. The transformed products were identified by comparing the HPLC retention times of the standards, and confirmed by LC−MS.
URI: http://hdl.handle.net/10397/34655
ISSN: 0888-5885
DOI: 10.1021/ie049509j
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