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.

Ag(II)-mediated electrochemical oxidation technique for organic radioactive waste treatment and analytical applications

“…It is of interest to investigate the possibility of using Ag(III) for these analytical applications in view of its much higher reactivity compared to Ag(II). Use of electrolytically generated [Ag(OH) 4 ] − for oxidation of recalcitrant organic dyes such as rhodamine in alkaline media was reported [19,20].…”