Water Science & Technology Vol 55 No 1-2 pp 209–216 © IWA Publishing 2007 doi:10.2166/wst.2007.034
Effects of ultraviolet intensity and wavelength on the photolysis of triclosan
H.-S. Son*, S.-B. Choi**, K.-D. Zoh* and E. Khan***
*Dept. of Environmental Health, School of Public Health, Seoul National University, Seoul, 110-799, Korea
**Center for Nanoscale Science and Engineering, North Dakota State University, Fargo, , ND 58105, USA
***Department of Civil Engineering, North Dakota State University, Fargo, , ND 58105, USA (E-mail: eakalak.khan@ndsu.edu)
ABSTRACT
The effects of ultraviolet (UV) intensity and wavelength on triclosan (TCS) photodegradation kinetic, efficiency, mechanisms and pathway were studied. The TCS photodegradation followed the pseudo-first order kinetic model at all UV intensities examined at the wavelengths of 254 and 365 nm and the photodegradation rate increased with increasing UV intensity. TCS photodegradation efficiencies of 90 to 98% and 79 to 90% were obtained at the wavelengths of 254 and 365 nm, respectively. TCS was degraded mainly by photon induced hydroxyl radicals while the direct photon reaction with TCS played a subordinate role. Chlorophenol, dichlorophenol and phenol were the intermediates detected in all experiments conducted. Dibenzodichloro-p-dioxin and dibenzo-p-dioxin were observed as the intermediates only at lower UV intensities investigated at the wavelength of 365 nm. Based on these intermediates, a complete TCS photolysis pathway was proposed for the first time.
Keywords: Mechanisms; pathway; photolysis; quantum yield; triclosan; ultraviolet
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