Formation of hydroxylated and dimeric intermediates during oxidation of chlorinated phenols in aqueous solution

The oxidation of selected chlorophenols (2-chlorophenol, 4-chlorophenol, 2, 4-dichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pent achlorophenol) was studied in aqueous solutions using UV/H2O2 and O-3 metho ds. The formation of oxidation intermediates was measured to elucidate thei r importance in the treatment of chlorophenols. Results indicated that chlo rophenols can be treated efficiently by the methods studied, but the dechlo rination of the compounds was insufficient. Analysis of intermediates in th e acetylated extraction fractions showed that hydroxylation of chlorophenol s and formation of dimeric products were involved in the oxidation of chlor ophenols in both treatment processes. The majority of the intermediates det ected were transient, and thus were not detectable after an extended treatm ent time. The presence of a complicated mixture of intermediates suggests t he need for toxicity testing to confirm the detoxifying effect of the chemi cal oxidation of chlorophenols. (C) 2000 Elsevier Science Ltd. All rights r eserved.