Photochemical Degradation of 2,4,6-Trichlorophenol in the Brij 35 Micellar Solution: pH Control on Product Distribution

Abstract

Surfactants have been used for separating organic pollutants from contaminated soils in soil-washing process. The extracted pollutants can be effectively degraded upon UV irradiation in the presence of surfactant micelles. The photodecay rate of 2,4,6-trichlorophenol (2,4,6-TCP) by UV light at 253.7 nm and photonic efficiency of 2,4,6-TCP degradation reaction were investigated at different pH levels with the addition of nonionic surfactant solutions above the critical micelle concentration (cmc). A continual examination on intermediates at all pHs was conducted and photochemical processes induced the dechlorination of TCP to form di- and monochlorinated intermediates and phenol. An additional reaction was observed when the initial pH level was above neutral, at which chlorinated hydroquinones were the resulting intermediates through photohydrolysis process. Two reaction mechanisms, one at acidic and the other at basic conditions, were proposed and verified by the evidence presented in this study.