Bis(2-chloroethoxy)methane degradation by TiO2 photocatalysis: parameter and reaction pathway investigations.
Haloethers are widely used in industry, and the release of these species into the environment is of great concern because of their toxicity and carcinogenicity. The present study deals with the photocatalytic degradation of the haloether, bis(2-chloroethoxy)methane (BCEXM), in the presence of TiO(2) particles and UV-A (lambda=365 nm) radiation. About 99.5% of BCEXM was degraded after UV irradiation for 16h. Factors such as solution pH, TiO(2) dosage, and the presence of anions were found to influence the degradation rate. To obtain a better understanding of the mechanistic details of this TiO(2)-assisted photodegradation of BCEXM with UV irradiation, the intermediates of the processes were separated, identified, and characterized by the solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) technique. To the best of our knowledge, this is the first report on the degradation pathways of BCEXM. The first step in the destruction of BCEXM is thought to be abstraction of a hydrogen by ()OH to form a carbon-centered radical which then reacts with O(2) to form a peroxyl radical. Peroxyl radicals react with one another and produce an alkoxy radical. The beta-bond fragmentation of the alkoxy radical produces different intermediates.
Chen
Chiing-Chang
CC
Department of Science Application and Dissemination, National Taichung University, Taichung 403, Taiwan, ROC.
Wu
Ren-Jang
RJ
Yao
I-Chun
IC
Lu
Chung-Shin
CS
D000838:Anions; D005019:Ethyl Ethers / Q000737:chemistry* / Q000528:radiation effects; D005609:Free Radicals / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010782:Photolysis; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
D000838:Anions; D005019:Ethyl Ethers; D005609:Free Radicals; C009495:titanium dioxide; C495703:bis(2-chloroethoxy)methane; D014025:Titanium