Degradation of pentachlorophenol as a model hazardous and recalcitrant organochlorinated pollutant using AgIII

Abstract

Environmental context Electrochemistry offers potential applications for environmental remediation. Pentachlorophenol, a highly toxic and recalcitrant halogenated compound, is degraded by a novel oxidant produced electrochemically, and the intermediates and products of the degradation are investigated. Cyclic remediation systems merit further study. Abstract The use of electrochemically generated Ag(OH)4− as a strong oxidising agent was evaluated for the treatment of a model hazardous and recalcitrant organochlorinated pollutant, pentachlorophenol (PCP). High-performance liquid chromatography (HPLC), gas chromatography with flame ionisation detection (GC-FID) or with electron capture detection (GC-ECD), gas chromatography with mass spectrometry detection and UV-visible spectroscopy were utilised to investigate intermediates and products generated during such treatment. From these, it was deduced that dechlorination occurred first, followed by an oxidative ring opening at the C=C bond that destabilised the remaining structure and generated tetrachloro-p-benzoquinone, 2,3,5,6-tetrachlorophenol, 2,3,4,6-tetrachlorophenol, 2,4,6-trichlorophenol (or 2,3,5-trichlorophenol), 2,4,5-trichlorophenol (or 2,3,6-trichlorophenol) and 2,4-dichlorophenol (or 3,4-dichlorophenol). In contrast to other remediation methods (e.g. incineration) no highly toxic molecules such as dioxins were generated by this novel degradation system.