Detoxification of synthetic industrial waste-waters using electrochemical oxidation with boron-doped diamond anodes

The electrochemical oxidation on boron-doped diamond (BDD) anodes of synthetic industrial wastewaters polluted with different aromatic compounds has been studied. This technology reduces significantly the organic load and the toxicity of treated aqueous wastes. The shape of the toxicity vs time curve depends strongly on the nature of the phenolic compounds, and especially on the substituent groups contained in the phenol molecule. For the oxidation of hydroxybenzenes a complex shape is obtained, with a plateau zone in the first stages of the electrolyses. This plateau zone is transformed into a maximum in the electrolyses of chlorophenols. In the case of nitrophenols, the toxicity index decreases at the same time as the chemical oxygen demand (COD) concentration, although the decrease in the toxicity is less significant than the decrease in the COD. All these toxicity profiles can be justified in terms of the nature of the intermediates generated during the electrolyses, but they cannot be directly related to the COD variation, which shows an exponential decrease. (c) 2005 Society of Chemical Industry