ELECTRO-OXIDATION OF CHLOROPHENOXY HERBICIDES: VOLTAMPEROMETRIC INVESTIGATIONS

摘要

Poorly biodegradable halogenated organic pollutants such as chlorophenoxy herbicides, often present in wastewater and sometimes in drinking water, are extremely harmful to human health. In recent years, the development of effective electrochemical means of mineralizing these organochlorine compounds, i.e. converting them to CO_2 and inorganic ions, has generated a lot of interest [1-8]. Various direct and indirect electrochemical treatment systems have been evaluated for the destruction of toxic organic pollutants in aqueous media. Anodic oxidation is an example of a direct methods, in which organic compounds are degraded by reaction with adsorbed hydroxyl radicals formed at the surface of a high-oxygen overvoltage anode. On the other hand, electro-Fenton processes involving the electrogeneration of hydrogen peroxide and/or ferrous ions are considered indirect electrochemical treatment methods. H_2O_2 can be electrochemically generated by the two-electron reduction of dioxygen in an acidic medium on graphite, reticulated vitreous carbon, mercury pool, carbon-felt, and oxygen-diffusion cathodes. This paper describes a comparative voltammetric study of the behaviour of four chlorophenoxy herbicides with different substituents in the aromatic ring.