Visible-light-sensitized dechlorination of perchloroethylene.
An aqueous reaction mixture containing perchloroethylene (PCE), a photosensitizer, and an electron donor was irradiated by visible lamps to facilitate a sunlight-sensitized dechlorination reaction. Various types of lamps, electron donors, and photosensitizers were examined, to compare the rates of dechlorination. Of the six photosensitizers evaluated, methylene blue was the most effective. Electron donors varied in effectiveness, as follows: trimethylamine > triethylamine > tributylamine. The intermediates and reaction products were identified by a purge-and-trap gas chromatography mass spectrometer system. The photosensitized dechlorination method degraded PCE via an electron-transfer-relay mechanism. Degradation products identified were trichloroethylene, dichloroethylenes, and chloroethylene. It seems a sequential dechlorination pathway was followed. The PCE dechlorination in a natural sunlight irradiation test was shown to be more effective than any of the simulated visible light sources. The result supports the feasibility of future development of solar-powered dechlorination remediation systems with the use of sunlight, nontoxic dyes, and electron donors.
Lin
Chitsan
C
Department of Marine Environmental Engineering, National Kaohsiung Marine University, Nan-Tzu District, Kaohsiung, Taiwan. ctlin@mail.nkmu.edu.tw
Jou
Chih-Ju G
CJ
Wang
Chih-Lung
CL
D008027:Light; D017319:Photosensitizing Agents; D013750:Tetrachloroethylene / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
D017319:Photosensitizing Agents; D013750:Tetrachloroethylene