DEGRADATION OF ORGANOCHLORIDE COMPOUNDS BY O-3 AND O-3 H2O2/

This paper presents the results obtained from oxidation with O-3 and O -3/H2O2 of a residual water coming from the production of dicofol and tetradifon pesticides, where chlorobenzenes, DDTs and its metabolites and other organochloride compounds were found. The oxidation processes were carried out using ozone (O-3) in basic medium (pH 9.4) at low do sage (0-1.5 g O-3 g(-1) initial TOC) and in the presence of hydrogen p eroxide (H2O2), with a 0.5 H2O2/O-3 molar ratio. During the treatment, many compounds were removed (dichlorobenzophenone, tetradifon, chloro benzene, trichlorobenzene) and their change in concentration at differ ent ozonation contact time was monitored. Other compounds like DDE rem ained practically invariable. This study investigated the formation of first ozonation by-products (FOBPs) in the wastewater, specifically c hlorophenols, by means of gas chromatography/mass spectrometry (GC/MS) and gas chromatography/electron capture detection (GC/ECD) analysis i n terms of the amount of time the O-3 has been in contact with the pro cessed sample. o-Chlorophenol, p-chlorophenol, benzenemethanol, n-chlo rohydroxibenzaldehyde, n-chlorobenzenemethanol, chlorobenzoic acid, et c., were formed during the treatment, due to the mechanism of fast and non-selective oxidation which ozone has through OH radicals, formed b y the decomposition of the O-3 molecule and accelerated by the presenc e of H2O2 in water. (C) 1997 Elsevier Science Ltd.