An ecologically effective water treatment technique using electrochemically generated hydroxyl radicals for in situ destruction of organic pollutants: Application to herbicide 2,4-D

The electrochemical production of Fenton's reagent by simultaneous reductio n of dioxygen and ferric ions on a carbon felt electrode, permits a control led, in situ generation of hydroxyl (OH.) radicals. The possibility of usin g electrochemically produced OH. radicals for solving environmental problem s is investigated. Continuous and controlled production of hydroxyl radical s was achieved by electrochemical reduction of O-2 in the presence of a cat alytic amount of ferric or ferrous ion. These radicals are used for remedia tion of water containing toxic-persistent-bioaccumulative organic pollutant s through their transformation into biodegradable compounds or through thei r mineralization into H2O and CO2. A widely used herbicide, 2,4-dichlorophe noxyacetic acid (2,4-D), was selected as a model for a toxic organic pollut ant. High pressure liquid chromatography (HPLC) was used to quantify the di stribution of the hydroxylated products obtained. Rate constants for the hy droxylation reactions of 2,4-D, 2,4-dichlorophenol (2,4-DCP), 2,4-dichloror esorcinol (2,4-DCR) and 4,6-dichlororesorcinol (4,6-DCR) were determined. T he mineralization of 2,4-D and its derivatives was followed by total organi c carbon (TOC) measurements. More than 95% of 2,4-D and the intermediates g enerated during the electrolysis can be mineralized.